Hi. I have stayed in USA around 7 years. I finished school in 2007. I am on OPT now.
My questions are following:
1. Am I non-resident alien or resident alien?
2. Do I have to pay federal tax,Social Security and Medicare taxes while on OPT ?
3. Which form do I need to use?
4. Will I get all my money back?

1) You are a resident alien. Your non-resident alien status probably expired in 2004 but, for sure, in 2005.

2) Yes.

3) Form 1040, 1040A or 1040EZ.

4) Probably NOT!