[Holyman007]

Pretty much what you need to do is read the stickies and FAQ. I would recommend upgrading to a new rom (since stock ones are usually cluttered with useless programs and very limited). Read gTen's post ^^. It tells you how to unlock your phone and how to flash into new ROMs.
There's tons to choose from in the ROM section but some I would recommend trying are MightyRom, JuicyRom, and Mr.X just to name a few.

Depends what you're looking for in a rom (looks, function, speed, battery life, etc).
Be sure to back up your contacts and info before flashing because you will lose everything in your internal memory (storage card will be fine).