Dormouse
Doesn't know that mice use holes.
Posts: 2,517
I'll try to touch on these briefly without oversimplifying/generalizing too much but also not getting too far off track since it's really a super complex topic.
1: Transvestism is a rather dated term and potentially offensive. That said, it historically [in the West] has usually been applied [eg clinically] for men who crossdress as a fetish, or for more general reasons. It is not an orientation, ie /who/ you're attracted to or how; however being /attracted/ to those who crossdress can definitely be part of an orientation or fetish [eg wives of men who crossdress].
2: Your "typical" crossdresser is as you mentioned straight, male, and often married. There are actually females who crossdress too, but given the West's double-standard on gendered clothing it isn't as "obvious".
3: A subset of those who crossdress consider themselves "bigender", ie that they have distinct "male" and "female" aspects and can have an entire other name/persona when dressed "en femme" versus "en homme". They may prefer to label their orientation not as straight/gay since those depend on gender/context but as "gynophilic" or "androphilic"- though these terms are not confined to bigender people. [This is /not/ to be confused with DID or multiple personalities.]
4: These are not to be confused with [quite often gay] Drag which is performance art [for both kings and queens respectively], but it's not uncommon [in my experience at least] for those who say they're attracted to people who crossdress to really mean drag kings/queens.
5: It is also not to be confused with transsexual people, who although often accused of crossdressing, actually are wearing the appropriate clothes for their gender identity. This can be confusing to those who aren't really savvy though, since eg bigender/genderqueer/drag/androgyny/hetqueer/&c can all be found under the greater "transgender" umbrella.
6: Dressing /apparently/ at odds with your birth-assigned sex is not new, you're quite correct. It goes back basically as far as human history, though often with different cultural consideration/implications, ie whether whether we in the West would consider them crossdressers when their cultures may not recognize the strict sex+gender binary dogma, and in many cases there exists a so-called "third gender" [though the Bugis culture recognize 5!], probably most famous are the hijra people of India, and the "two-spirited" in some Amerindian cultures, but there are many many other examples, one of the more interesting being a [dying] Albanian practice of "sworn virgins" where if a family didn't have enough male children or a father died or such, a daughter could begin dressing and living as a [celibate] man with all the standing/rights/privileges thereof to help support the family.
So long story short, despite the common overlap/conflation, a person's: sex [which is more complicated than XX vs XY], gender identity, gender expression, orientation, and fetishes are all discrete categories.
[/queer theory class for the day]
Also, I can kill you with my brain.