To echo what others have said....

My experience is that gays and lesbians don't "get" crossdressing and trans issues any more than hetros. And yes, they also assume a man who crossdresses is gay.

Overall, my experience is that gays and lesbians are more tolerant. They may not understand us, but they're generally willing live and let live -- probably due to being familar to what it's like to be considered an outsider themselves. That said, certain segments of the lesbian community aren't trans friendly -- they still hold to a view that MTFs are at best making a mockery of women and are worse trying "to colonise feminist identification, culture, politics and sexuality" as Janice Raymond put it in her infamous "The Transsexual Empire." And a gay CD I know experience the worse harassment she'd ever had on Castro Street in SF.

Marina -- Being TS isn't inherently being "technically" homosexual because some MTFs are attracted to men and some to women. Unless you want to argue that someone's "technically" homosexual pre-op and the hetro post-op (or vice versa). Which is why it's far more useful to think in terms of androphillic or gynophillic (i.e. attracte to men or attracted to women).

As far as why the association of CD = gay, it's part of a long-standing false equivalence that "unmanly = feminine = gay." (And not it's not that most drag queens are TSs, the vast majority of them are gay men, thank you very much.) In part it goes back to theories several centuries ago that gays and lesbians were "sexual inverts" and therefore the thinking was that they must have been womanish men and mannish women. Also it probably is related that a number of gay men did crossdress in the late 1700s and early 1800s as a way of advertising their homosexuality. While female impersonation was predominately a hetrosexual artform up until WWII, afterwards for various reasons having a drag performer was a covert way of signaling that a club catered to gay clientele in an era when any overt advertising would've resulted in the club being shut down and the owner probably carted off to jail.

As far as the great degree of gender varience one see in the gay and lesbian communities, I think it's the flip side of the greater sexual varience seen in the trans community. Once you've stepped outside of "normal" in one dimension, it's easier to acknowlege "non-standard" feelings in the other. So you get feminine gays and masculine lesbians, although neither necessary get the greatest respect within the gay and lesbian communities (neither do femme lesbians), and CDs who are more willing to acknowledge bisexual fantasies, desires and behaviors. (Although arguably, based on the Kinsey spectrum, I don't think bisexuality is higher among CDs, I think they're just more likely to acknowledge it.)