Welcome aboard.
http://www.thamnophis.com/caresheets/index.php?title=Garter_Snake_Care_Sheet
Plus there are discussion threads on every relevant subject.
1. About the same length as the snake. Bigger is better.
2. A couple of hides and maybe a something to climb on. Fake plants if you feel like it, it's all the same to the snake as long as there are hides available.
3. Regular tap water is fine.
4. Worms should only be given on occasion. Fish and mice is the best alternative. How often depends on what and how much you are feeding it.
5. Never. Fish and mice.
6. It's rare and you shouldn't try to force feed it unless you know how to do it correctly and even then only if it's absolutely necessary.
7. That's something you have to figure out for yourself. Some don't name their snakes at all and others (like me) don't even use the names they give their snakes.