Answer:
Answer 1: Sounds like a question for a professional piercer! But, the most standard places are in the middle (actually, slightly off center; it's really painful to get it RIGHT in the middle where it comes out at the bottom and so most people don't), and underneath (you can get that "webbing" pierced). If people get multiple tongue studs, they usually make them in a row (put one in front of the standard one, for example), but you can get them in the sides too.
With any tongue piercings, it's very important to make sure you don't hit major veins. Also, not everyone's tongue is suitable for the webbing piercing. Mine wasn't :( A good piercer will refuse to do it if you don't have enough of a web.