I'll answer the questions then give my reply.
1. Go to an eye doctor. Any one will do as long as it's a legal practicing eye doctor (a friend in eye doctor school is not who to go to, for example, let alone anyone with no degree in it).
2. That depends on insurance I think. I'm not sure if an exam is cheap. But if you are on a good insurance plan (usually if you are on a parent's good pan, that would cover everything but a co-pay, which the price is decided upon by the insurance company).
3. Why? Do you like being able to see and not have effed up eyes? If so, then that's why.
4. Yes, ones that help your vision are always better. I too need glasses so if I were to get contacts, getting vision helping ones would be ideal for me. If you can see good enough without your glasses, then it doesn't matter. Like, I only need mine to read far away..So I don't "need" them as much as are just there for a specific use.
Most people that get contacts are not doing it right and are risking their vision "to look cool". Don't add to that. If you can't afford it, it's way better to simply not have them. It isn't a life or death need, so there is no reason to risk your vision and make it worse than it already is (since you say you need glasses, that means your vision is already not good, don't make it worse just to look cool.