Achievements are unlocked by accomplishing the listed task and will give you the listed number of gamer points. If you have an X-Box 360 gamertag, you can log in using this same gamertag and the gamerpoints/achievements will count the same as if you were playing the 360 version / any other X-Box 360 game.

To get all of the 5 gear kits, simply drop the weapons of your existing kit on the ground before talking to the quartermaster. Usually he will take back the items from your previous kit and give you your new one, however since they are on the ground he can't. You will receive your new weapons and get to keep your old ones.