In response to the original poster's first question I would like to direct you to my response on this thread: Meaning of the valediction "Yours, &c.", reproduced here. Please excuse the some irrelevant items as I was answering a different question.
"I am not particularly well-versed in this subject, but I do think I should chance an answer here.
The 'et cetera' or '&c' part of the valediction 'Yours &c' is a contraction for a common valedictory statement used during earlier eras of English, as stated before, when relationships between the sender and recipient were more clearly defined--the contraction being of the formal
"I remain, sir, your most loyal and faithful servant"
Used, perhaps, even in correspondence between peers as a respectable gesture of putting oneself in the service of one's correspondent.
But how did we come to 'Yours, etc' from here?
You'll notice that the form used above is 'YourS' and not 'Your', which is used in the expanded valediction.
This is because the 's' is contraction for 'servant' and as such 'Yours etc.' meant 'Your servant, etc (most humble, loyal, faithful, sincere. . . .)' and thus even the more common 'Yours faithfully' and 'Yours sincerely' used today meant 'I remain, sir, your most faithful servant' and 'I remain, sir, your most sincere servant'--the former of which is used when the sender does not know the recipient in person.
And thus more archiac version of 'Yours, &c' would be 'I remain, &c' which you will still find appended to some letters today.
Hope this is satisfactory."