well i been buying apps (games and etc) from the app store from diferent account (dad's, brother's, sis's accounts) now my question is if i jailbreak it i lose all the app i had downloaded? i can make a backup and then use it? i dont feel like donwload each app after jailbreaking

The jailbreak It self will not delete anything.

U will not loose your downloaded apps or anything else IF the jailbreak goes as It should do.

But make sure u have a ios that suports the jailbreak method u gonna use.

As always u should do a backup before u jailbreak your ipad.