Why do Orthodox rabbis seem to be avoiding answering questions about same sex marriage and trans-genders?

You won't find any (!) Torah-true rabbi in the world, who avoids or side-steps rebuking on the issue of transgenders or same-sex "marriage”. The only thing is that you may find rabbis who "strategically" prefer not addressing the issue in public, so as not to lend legitimacy to the very question, just like I don't remember the last time seeing a rabbi deal with the question whether a Jew is allowed to eat pig. If you find a rabbi who’s voice is unclear on the issue, he is by definition, non-Orthodox (btw, the term "Orthodox" was invented by the Reform, and their connotation isn't that complimentary- in general it's unwise to let your opponents define you!).