Go to game marketplace, go to game add-ons and look for Halo Reach. You need to be with Xbox live if your not.
first u need xbox live there is sometime updates too
well,you have to download them again.or else theres something wrong with your xbox 360, that is not allowing it to download
Buy a hard drive n go to file share Or buy noble map pack or defiant map pack. For the bungie made maps
No you need a Bungie.net profile and a Xbl account