Yep. I have all of them, and I am Prestige 1 and Level 70, except the Prestige 10 title.
Yes you lose everything but titles and emblems
By getting into a tenth prestige lobby.
When you prestige, you earn another slot for "Create a Class". You can also earn different titles after you prestige.
MasteryUnlock all Weapon Attachments500 KillsPrestige Veteran I250 HeadshotsPrestige Master I2500 Kills Silver PrestigePrestige Veteran III1000 Headshots Gold Prestige Prestige Master III
By finishing all prestige challenges (you find them under your normal challenges when you prestige).
you have to get 250 knifing kills in one prestige.
no. for prestiging you only unlock new titles/emblems extra custom classes and a new symbol.
You can Prestige in MW2 precisely 10 times.
you keep prestige challenges, titles, and emblems. You lose everything else you have earned
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
From prestiging in modern warfare 2 u get an extra custom class and new emblems and titles.
No