The What and Why Not...
The distant origin of the modern figurative sense of 'kiss of death' is well-known. For the lexical sense of the phrase shown variously by the two references given in the question,
- a fatal or destructive relationship or action,
(Dictionary.com Unabridged, Random House, Inc.)
- thing that signifies impending failure,
(Online Etymology Dictionary, Douglas Harper)
and more comprehensively defined by OED Online,
a seemingly kind or well-intentioned action, look, association, etc., which brings disastrous consequences
that distant origin is
[from] the association with the kiss of betrayal given to Jesus by Judas in the Garden of Gethsemane (Matthew xxvi. 48–50).
Inherited from that origin, and common in modern uses, are connotations of betrayal and disloyalty.
Abundant evidence from the US popular press contradicts the notion that the proximate origin of the modern figurative sense was "in Mafia movies of the forties", and that it dates to 1944-1950. Instead, appearances in the popular press suggest the proximate origin of the modern sense was in political and other contexts in the late 19th and early 20th centuries.
...of Your Second Question
The use in Billboard in 1944 (the "once dial-twisting words, 'This is an electrical transcription,' do not, as they did a short time ago, mean the kiss of death for a program") has no connection with gangsters or gangster movies, being instead a quite diluted use of the figurative phrase with reference to "an action" (the twist of the radio dial to change stations) sponsored by a circumstance (the program being prerecorded rather than live) that "signifies impending failure" (the cancelation of a radio program due to loss of listeners).
In addition, the use in Billboard has, other than the loose definitional similarities drawn out in my preceding paragraph, few of the characteristics of the modern figurative sense. The twisting of the dial and the circumstance of the radio program having been prerecorded are neutral at most; they are not "seemingly kind or well-intentioned", and they do not on their face connote anything more than a trivial disloyalty (as contrived by its promoters and advertisers, that is, disloyalty to a radio program) or betrayal (only of that contrived loyalty). That action and circumstance do, however, sometimes bring about the failure of the radio program.
...and of Your First Question: Evidence
While the earliest and silent gangster films were made in the early 20th century (around 1905, depending on definitions; see History of Gangster Crime Films), no readily available evidence suggests the phrase 'the kiss of death' was used in, or in association with, those films or later gangster films through the 1930s. To entirely rule out such a use, and association with, gangster films, an exhaustive viewing would have to be undertaken; I do not propose to undertake it, not least because the evidence that is readily available, as well as the chronology of that evidence, suggests other proximate origins are much more likely.
Beyond instances that appear to me to be tangential to the modern figurative sense at issue here, instances wherein a literal kiss brings death consequent upon the communication of disease or other direct causes (poisoning, etc.), the first instance intimating the modern figurative use appears in a political context:
The senatorial kiss (of Mahone and Riddleberger) he called the kiss of death — of political death.
From a speech given at the Democratic State Convention in Virginia, as paraphrased in the Richmond Dispatch (Richmond, Virginia), 31 Jul 1885.
Even in context, the meaning of this at first eluded me, in part because of interference from the meaning such a use would be likely to have now, wherein a "senatorial kiss" would be a figurative reference to public endorsement of one candidate by another. (Later instances which will be presented here show that the interfering sense does arise prior to the putative 1940s gangster movie origin of the phrase.) Digging a little deeper, however, I discovered that the reference was to an literal kiss, one that was thought by the speaker quoted above (from a speech given at the Democratic State Convention in Virginia) to presage political 'death':
A New Species of Kiss. — Was the spectacle on the platform of the Republican State Convention in Virginia, where Mahone and Riddleberger not only "hugged," but ecstatically "kissed" one another, one likely to attract young men to the Republican party?
Staunton Spectator, 29 Jul 1885.
So the use refers to a literal kiss with no suggestion of betrayal or disloyalty, but presented as likely to signify the figurative political 'death' of Republican political control of Virginia in 1885. This is close, but not quite the modern figurative sense of 'kiss of death'.
Next, in 1898, comes an instance in an industrial context. Again, the sense was at first unclear to me, but I later uncovered further context that explained the use:
The Kiss of Death. A Story of the Modern Slavery by People with Memories.
...About the "Kiss of Death," the operatives daily courting of disease; ....
The World, New York, 28 Jan 1898.
That teaser from the Friday edition for content in the Sunday edition is clarified adequately by another teaser in the Saturday edition:
The Kiss of Death — a word-artist's phrase. The "shuttle bussers" who thread bobbins with their lips kiss death 1,000 times a day; the lint gets 'em.
The World, New York, 29 Jan 1898.
The 'kiss' here is semi-figurative, being descriptive of a procedure used in the course of mill employment; as in the 1944 Billboard use, this 'kiss' seems neutral at most, no betrayal or disloyalty being intended, although the 'kiss' is "a seemingly...well-intentioned action...which brings disastrous consequences", and so roughly fits the OED definition of the modern figurative use.
As an aside, references to the 'kiss of death' in later publications, around 1911, reveal that the cause of the industrial workers' deaths was not "the lint" as contended in the Saturday edition of The World. The cause of the deaths was "consumption", that is, tuberculosis, and the 'kiss of death' mentioned was outlawed, finally.
While betrayal, disloyalty, or profound hypocrisy (as in the mafioso's kiss) lie behind the modern figurative use of 'kiss of death', none of those are a necessary part of the sense as defined by Dictionary.com or the Online Etymology Dictionary. They are hinted at by the "seemingly" in the definition from OED Online. If those perfidies are indeed part of the essential use of the modern figurative phrase, none of the instances from 1885 and 1898 quite conform. In that case, evidence for the origin of the modern sense of the phrase did not appear until this 1928 use in a political context:
The vote he received in the primaries tells the story. He got the kiss of death — a kiss of a Judas, who was urging his nomination on the front page and secretly in alliance to nominate another candidate. Charles H. Williams obtained the pledge of whole-hearted Clark support through his friends and managers, and within a few days of election, saw the Clark paper in Missoula come out for Joseph M. Dixon.
The Helena Daily Independent, Montana, 24 Jul 1928.
The 1928 use of the phrase in a political context with the modern figurative sense is followed by another in 1930:
Lewis said nothing about the Mayoy's [sic, = Mayor's] change of front. But one of his lieutenants, upon being promised anonymous expression, said that "Thompson support is worse than the kiss of death to the candidate so unfortunate as to receive it."
The Cincinnati Enquirer, Ohio, 1 Nov 1930.
This 1930 use is not quite so clear-cut as the 1928 political use. The context suggests the use refers to political backstabbing by way of hypocritical, that is, disloyal, endorsement and support. Mayor Thompson of Chicago had previously helped a Mrs. McCormick obtain a Republican senate nomination before switching his support to Mrs. McCormick's Democratic opponent, Lewis. Mrs. McCormick responded by announcing that she was "grateful to be publickly relieved of the stigma atached to support from the Mayor." One of Lewis's lieutenants then made the anonymous statement shown.
The evidence shown so far indicates the origin of the modern sense of the figurative phrase was political and industrial, from the late 1800s or early 1900s, depending on how finicky you are about the niceties of sense. If you are willing to accept the loose definitions proposed by Dictionary.com and Online Etymology Dictionary, evidence in the popular US press dates the origin to the late 1800s; if, on the other hand, you insist on the nuances of perfidy inherited from 'Judas Kiss', as in one interpretation of the definition from OED Online, the origin may date to the late 1920s.
If a false equivalence between popularization and origin is drawn, the origin of the modern sense of 'kiss of death' might be said to date from the 1930s. In 1931, widely reprinted stories proliferated about an unfortunate woman, Anna Collins (aka Anne Burke, Margaret Sullivan), with the moniker "The Kiss of Death". According to the reports, the title was given to her as a result of seven of her gangster boyfriends meeting violent deaths.
Stories about, and mentions of, Anna (aka Mary, Margaret, Martha) Collins continue through at least 1936. In 1933, Anna Collins was joined by another 'death kiss' woman associated with the multiple deaths of gangsters, Viola Morin. In 1939, and into the 1940s, the title was passed on to a woman reputed to be a for-profit poisoner of husbands and boyfriends.
Interspersed among those stories and mentions of 'kiss of death' in the context of criminality are uses in various other contexts, with political contexts prominent among them. Other contexts include cinema (The Death Kiss, 1933, a suspense drama, not a gangster movie; 1935, a horror movie; 1936, a suspense-adventure drama), music (1933, the title of song in a radio program), political (1935, a 'kiss-of-death' file of form letters to be sent to out-of-favor politicians, purportedly mantained by Roosevelt; 1935, a letter of dismissal sent to a female member of the Federal Board of Parole; 1936, a reference to the GOP nomination; 1938, a reference to the backing of a non-partisan league; 1939, a reference to letters attempting to extort political contributions from a prison warden; 1939, a reference to Roosevelt's supposed opposition to the neutrality act; 1939, a reference to international trade pacts).
Uses of the phrase in political and other contexts continue and are (relatively) common throughout the 1930s and 1940s.