After you reach 70 you have to get more xp to be able to prestige (around 80k xp). Every odd prestige (1,3,5,7,9) you get a new custom class. You get a new emblem and title for every prestige. You can prestige a total of 10 times. When you first prestige you gain the prestige challenges in the challenges section and prestige challenges for weapons. These prestige challenges DO NOT reset when you prestige again.
You get the option to be able to "Prestige" when you reach level 70. Once you prestige, you will get titles corresponding to the number of times you have prestiged. E.g: Prestige 1 = The Prestige Prestige 2 = Round 2 Prestige 3 = Third Time Charm Prestige 4 = 4 The Record etc...
Just play till you get 10th prestige lobby invites. They'll happen a lot.
no you don't have to prestige in codmw2 if you want you can, just by simply pressing prestige in the barracks option in the xbox360 live menu. But if you do you will lose all of your weapons, killstreaks, and perks. however you will be able to go up more ranks, and kepp your titles and emblems.
no
no
level up
yes
No.
You learn how to play better?
Codmw2 was probably bought more than halo reach because halo r is newer. Though I am a halo reach fan.
No only on campaign is split screen
Possibly the TAR-21 or the Barret 50 cal