What are some of the legal obstacles/benefits for Caitlyn Jenner?

Now that the former Bruce Jenner (male) has become Caitlyn Jenner (female) there are some ramifications for her that most people don’t have to deal with or probably don’t even think about.

I’m guessing that as a male, Bruce Jenner, who was/is married to Chris Jenner (although they’re getting a divorce) considered himself to be a heterosexual male. Now that he has been transformed into Caitlyn Jenner (legally yet?) if he still has a sexual preference for females (not necessarily for Chris Jenner) is she now considered to be a lesbian?

If she now (because of the hormone treatments or maybe because she always felt this way) is attracted to men, does that make her a gay male, or a straight female, or both, or neither.

You hear that sexuality and gender are fluid, but in our society, people still tend to look at people as being either gay/straight/bi, without their preferences and genders switching back and forth across an invisible line.

Now that Bruce is Caitlyn, is it legal for her to marry a male in the states where gay or same sex marriage is still not legal? If so, what characteristics does a person have to possess to make them legally considered to be of the “opposite” sex of someone they might want to marry? Do they have to have a complete sexual re-assignment surgery? If they were born as genetic females, does having a double mastectomy constitute being “opposite” enough? Maybe they only have to have taken hormones that are the opposite their birth gender to be considered to be “opposite sex” enough. If they just have to take hormones, is there a delegated time frame for taking the hormones? What if someone takes the hormones for years, but then changes their mind about switching genders? What if they only take hormones for a month and want to get married right away? Are those folks considered to be “opposite sex” enough?

Does a person who does any of the above (surgery/hormone treatments) or simply by dressing/living as a person of the opposite gender, have to get a new birth certificate stating that they are now the opposite gender from the gender they were born with? If so, how does one go about that legal process? Would a person that changes genders who wants to get married to someone of their same original gender, need to get a new birth certificate stating that they are now of the “opposite sex”?

What about already married couples, who decide to stay married after one of the spouses gets gender re-assignment surgery, in a state in which gay or same sex marriage is not yet legal? Are they still legally married? If so, how does the law apply to them now that they are technically in a same sex marriage?

Lots of questions. Hopefully someone with some legal knowledge of this subject can jump in here. This question itself kind of proves the point that banning gay or same sex marriage is kind of silly, since no one can really know who is male or who is female, and it doesn’t/shouldn’t really matter to anyone unless they are part of the actual couple that wants to be married. Right?