I don't know which communities you're talking about, but anecdotally I have to say I've found trans bars and support groups to have a much broader range in race, class, and origin than any other places I typically go.
Also, low testosterone you describe in that paragraph is not implicated as a cause of transgender behavior, with people generally being in the typical range for their birth sex before transition, which includes outliers with very high testosterone levels. Giving people additional testosterone has been tried and not been found to "cure" transgender behavior.
Relying on made-up facts for an entire paragraph of your purpose statement is not very encouraging.
I read an article once about the hijra, a third gender in India. What surprised me at the time was that some hijra were adamant that they were not transgender in the western sense, seeing it as foreign and strange, whereas others would have preferred a binary transgender identity had it been available in their culture. So some strongly viewed hijra as what they really wanted to be, but others saw it only as a consolation prize because their culture didn't include the concept of transitioning to the other binary gender.
I walked away from this thinking that the cultural component of gender can't be overlooked. Gender is ultimately a compromise between the individual and categories provided by the culture. I can even imagine, that if one had two very different cultures and were able to completely replicate a particular infant, atom for atom, it's possible in one culture they would identify as male, and in the other as female.
Humans are made of both biological and memetic (social) stuff, though. It's famously difficult to ascribe any particular behavior to just one or the other -- the old nature/nurture debate being one aspect of that -- but even if you could, you can't necessarily describe one side of that as more "real" than the other side -- I am both my flesh and its neural activation patterns. One reason I believe most transgender people describe a purely physical (brain) basis is that using the language of desire is severely socially proscribed: it's not viewed as OK to merely say "I want to be a man/woman" the same way someone can say "I want to be an architect", although in both cases a person may simply be looking around at the various roles their society has on offer and finding some desirable than others.
This phenomenon isn't limited to transgender people; even 15 years ago gays and lesbians were viewed more negatively by society, and magazines would run articles about "the gay gene," despite the lack of evidence for its existence. Nowadays, in a much more tolerant culture, you can find people who say that they "choose to be gay." A similar evolution in transgender self-description could happen if society becomes more tolerant.
So, I think this is actually evidence simply that behaviors or accomplishments viewed as highly unusual (either positive or negative) are often ascribed to a physical basis, whereas anything perceived as being in the normal range of human behavior in the culture is seen simply as the individual's choice or self expression. This doesn't actually tell you anything about the cause of the action or desire -- we can't do the kind of experiments that would be necessary to find that out. For all we know, desiring to be a particular gender, or desiring to have a particular occupation are similar mixes of built-in brain organization, body chemistry, psychological imprinting, culture, and both conscious and subconscious weighing given the individual's other abilities and limitations.
Improving dream recall isn't necessarily important for lucid dreaming -- I practiced lucid dreaming for some years without any explicit attention to it. I can imagine ways it would be helpful: analyzing your dreams will help you recognize when you are dreaming, plus there's not much point to a lucid dream if you don't remember it.
My fears are more on the opposite side of things; some people advocate lucid dreaming methods where you slip directly from wake to lucid dream, but this requires passing through some rather terrifying states of consciousness I can't bring myself to intentionally experience.