Alexithymia refers to a state wherein a person cannot understand or describe his or her feelings, and means literally "without words for emotions". Is there a term (psychological, medical, or otherwise) for someone who is overly conscious of and articulate about his or her emotions?
Emotional intelligence (EI) is the ability to identify, assess, and control the emotions of oneself, of others, and of groups.
The EI page on Wikipedia also goes on to state:
Alexithymia from the Greek words "λέξις" (lexis) and "θυμός" (thumos) (literally "lack of words for emotions") is a term coined by Peter Sifneos in 1973 to describe people who appeared to have deficiencies in understanding, processing, or describing their emotions. Viewed as a spectrum between high and low EI, the alexithymia construct is strongly inversely related to EI, representing its lower range.
A site that appears to be dedicated to this subject proffers Emotional Literacy as "the opposite of Alexithymia":
Emotional literacy is defined as:
The ability to express feelings with specific feeling words, in 3 word sentences.
For example, "I feel rejected."
There is a somewhat slang phrase, emotional dumping which, according to the Urban Dictionary, means
Unloading all of your emotional crap unmercifully onto one or more of your friends.
In my view #1 "what is the opposite of “alexithymia"?" and #2 "Is there a term (psychological, medical, or otherwise) for someone who is overly conscious of and articulate about his or her emotion?" are two different questions, since the answer to the second one would presumably have a normative color that alexithymia need not have if it is being used merely as a description.
Compare the difference between blind vs.sighted and blind vs. gawking.
Anyway for #1 people often describe being "tuned into" one's emotions or that someone is "exquisitely sensitive"; for #2 people often say that someone is "oversensitive" or "oversharing" or an "oversharer" or even "too intense"--but "too intense" can mean a lot of other things, too. Even "irritable" or "manic" can capture some of the phenomenon of "excessive emotionality." Then you've got "histrionic" and "melodramatic" as well.
Actually "exquisitely sensitive" may be the best one because that term, like the components of your original question, is ambiguous between description and judgment.
PS Take a look at this: http://www.wrongplanet.net/postt192380.html