Mormonism held it's first official meeting on April 6th, 1830 (I think...o_O).
Actually taking the term "trinity" literally is not a common Christian thing to do. Most Christianity seems to believe in the Trinity actually being one God calling himself different names...it doesn't make any sense, and all they ever answer that with is "yeah, it's confusing, but don't worry, it's true." -_-
The church's response to you asking why God would have us go through all this to gain eternal life as perfect celestial beings would be: "We have been given revelation from God that this is the absolute truth." My personal response would be "Why not?" =p
And in LDS doctrine, homosexuality is a sin against God, though really gays are still treated with respect and as human beings. Since it's a sin, they aren't allowed to participate in certain covenants and activites and stuff if they delve into being homosexual. Actually an LDS interpretation of the major sin of Soddom and Gomorha (I slaughtered that spelling...) was indeed homosexuality, which makes sense if you read the King James version of the bible and hold certain words to mean certain things throughout the bible...
But yeah, if you commit to being gay, you're not considered an active member of the church. It's a major accusational problem the church is dealing with, as you can imagine.
...god, I should probably stop talking about Mormon stuff, I sound like I'm a member again o_O