Hello from Pennsylvania!
I got banded on December 30th, 2010, so all my memories and experiences are pretty fresh (if not ongoing!).
Depending on your BMI, there are different diets you should go through prior to the surgery. The purpose of the diet is, from what I've gathered, good because: your liver likely needs to shrink prior to surgery; you need to acquire better eating and lifestyle habits to get you ready for the lifetime change ahead; your doctor wants to see if you're serious about losing weight, and; many insurance companies require it. I lost 22 pounds prior to my surgery and have lost at least 12 pounds since.
Meetings are good for many people because you get to be in a room of people who totally understand where you've been, where you are, and what roadblocks you'll encounter on getting to where you need to go. Being at a meeting helps keep you honest too--if you're too insulated from others you're more likely to "fall off the wagon" diet-wise.
And of course it affects your eating and drinking; that's what got us into this trouble to begin with! If we don't take a very critical look at what got us to where we are, we'll not succeed. Eating as you used to eat after being banded is at the least foolish and at the most dangerous. But the process goes beyond eating. Exercise has to become a part of your daily routine, as well as avoiding/modifying those situations that contributed to your overeating. So yes, it's a lifestyle change--a necessary lifestyle change.
I have not experienced very much pain at all. I'm more tired than anything else, and that's getting better too. I am following the diet plans my doctor & nutritionist supplied me and am not cheating. My stomach needs time to heal. If I ate huge portions like I used to I could do major damage to myself. Anyhow, I like stepping on the scale and watching my weight go downdowndown.
It doesn't sound as if you're intellectually and emotionally ready for this. Work hard on that. It is a permanent and necessary change to your life (I'm assuming necessary, as your doctor wouldn't suggest it if you weren't probably morbidly obese). It is a tool to help you in your weight-loss journey, but it doesn't do the work for you. That's up to you.
I wish you the best, northern neighbor. Good luck & bonne chance!