1) Those are not actual programs. They are launchers. They are pushed by your carrier. You can't delete them and even if you did, they would get pushed back to the device. They don't take up much space. Just hide them and forget about them.
2) No. You can't use in on another network. And CDMA devices cannot be unlocked.
3) Keep an eye on your File Free. Delete stuff you don't need (messages, apps, etc). Be sure all your media (pictures, ringtones, music) are on the Media Card and not in the device memory. CLOSE applications when you done with them rather than just backing out of them.