Its entirely up to you. If you prestige you start over but you get new title and emblem and you keep your old ones. If you don't prestige you just stay at level 70, wasting your XP and doing nothing. I would prestige, but its your choice.
You can Prestige in MW2 precisely 10 times.
Theres no need to prestige unless you want the extra tittles and emblems on mw2.
Well if you prestige in MW2 then you should get a token, and then on MW3 when ever you get to 80(:
in cod black ops there is a 15th prestige and in mw2 there is only 10 prestiges because to prestige in mw2 you have to get to level 70 but in black ops you only have to get to level 50 to prestige
No
NO
If you get prestige, you get night vision goggles!
By entering prestige mode 10 times.
you should do all the easy challenges you could do
Reach Prestige 1 and Level 69.
Get to level 70 then go to barracks and pick prestige mode
100