Mw2 Prestige Question?

I just ogt to lvl 70 and am thinking about prestiging...however, i hav a few questions...1. (just say i have all camo, acheivements and things for a gun)i know they willl restart, but once i earn that gun back do i keep all the camos???or do i have to start all over again 2. if i have the mastery acheivement on a gun, how many titles do i get 3. do you think its worth restarting 4. do all my acheivements restart and what happens when i do them again (ex. drop a crate on an enemy for a game winning killcam) just say i already did that one and got a title for it, what happens when i do it again???