is it possible to creat a new player account and keeping the same grade or i will have to start all over again

New name=new account. So yes you would have to start over. Unless there is some "hack" to import your old MP data to your new account.

actually

new account = new name and you DO NOT lose your xp, your xp is tied to your game not your account, your xp is stored locally in your my doc folder and should be backed up because it can easily be carrupt and you lose everything.

also XP is useless, you start with the 2 best weapons any way the mk.23 and the famas.

to be honest the mk.23 is all you need and you can kill any assault or shield weilding player out there