As far as retirement stands right now, at 20 years you are eleigible to retire. You will be paid 50% of the average base pay for your last 3 years. For every year you go past 20 you add an additional 2.5% to your pay. So if you stay for 30 years you woild collect 75%. Also you keep full benefits as well as your px and commisary privelages which means you can shop on post tax free. You can take any major you want in college. I am in special forces and my last team leader, which is a Captain or O-3, was a history major. The military is obviously not helping his future in that field, but you can have pretty much any degree to become an officer.