1) First all they do is put glue on your teeth, individually, then put the bracket on, dry it with an electric dryer tool, and after all that is done, they put the wire in. As long as the wire isn't poking or jabbing into the gums in the back of your mouth, the entire process doesn't hurt at all.
2) Zero. When they put IN the braces, it didn't hurt. It's afterwards that is painful.
3) 6. It isn't a pain so much as an uncomfortable "GAH I want to rip these out." feeling. Your mouth will feel tight and itchy almost, like your teeth are itchy. It's hard to explain. Most of the pain will be felt on the inside of your mouth, like your cheeks and lips, because all that metal will be scratchy. You WILL want wax.
4) It depends on what your orthodontist tells you. Mine was every five to six weeks, but now it is every 3 weeks. It changes alot. And whether or not it hurts depends on the progress you make. It only hurts when they put the elastics back on, because the elastics (the little, colorful rubber bands around your brackets) are very tight, and there will be a lot of pushing and pressure involved in putting those on. My pain factor is more level 4.
5) That isn't something I can tell you, only your insurance people. But the payment (most of the time) will be broken down into a payment plan and if you go with a good orthodontist, they may be able to work with you.
6) You can't break the wire with food, you can only pop off brackets, and that doesn't hurt, its just very uncomfortable. Avoid crunchy foods that take a lot of chewing, like ice and crunchy cheetos, suckers, jaw breakers, pretzels etc. After a while, you will learn how to chew in a way that wont pop anything off. They will usually give you a list of foods that aren't smart to eat. Just be careful.
7) You'll get used to them after about 3 weeks, if not less. That's how long it took me. After about a month you'll forget you even have braces.
8) Depends, I've known people who've had to have theirs for 4 years, and some only a year and a half. It really depends on the severity of your teeth. If they are moderately bad, like mine were, they usually only keep them on for about a year and a half to two years. Mine will be off after a year and a half. But if they are bad, to where your mouth and the way you chew is corrupted by your teeth (rare cases) then it will for a while. Just until the teeth and the roots are straightened up with eachother.
Braces seriously aren't the horror story many people say they are. They are more a nuisance than a pain. And the outcome is worth it. So don't be scared, it's really very overestimated than how it actually is. (: