Star Trek Questions

I love Star Trek. I loved it when I was a kid when the series first came out. I don't own a Sterfleet uniform, and I never go to Trekkie meetings, but I catch all the movies and the shows. I'm bummed that there is no current iteration of Star Trek on the tube nowadays.

One of the things that was supposed to make Star Trek so popular was that it was optimistic about the future. Humans would go on to do great things and solve a lot of our problems.

I have a few questions, though.

What happened to all the Chinese people and the Mexicans?

Do people in the future still go to the bathroom? If so, why would the uniforms in the Next Generation consist of one piece jumpers with no fly?

When all the other systems go off line all the time, the artificial gravity never seems to fail. Why is that?

When people go "out of phase" they can walk through bulkheads. How is it that they don't go through the decks as well?

If a transporter malfunction can make people younger, as in the episode where Picard and some others are turned to children, why wouldn't people rejuvenate all the time by tinkering with the transporter controls?

Do members of Starfleet get paid? Is there an accounting department?

How is it that species from different planets can interbreed? Wouldn't it be bestiality to mate with another species?

If you ride a horse on the Holodeck, won't you eventually run into the wall? If you have sex with a holographic character, where does the semen go when you end the program? Remember when Whorf's brother had a village of aliens in a Holodeck? What happened to all their poop?

How could a society as antiintellectual as the Klingons have developed warp capabilities?

Is the Federation of Planets really just an organ of Imperial Earth?