oosk, you need to be extra careful with these nuts, they are really weak and strip extremely easy.
as for how to remove the stud. Go to NAPA, they have a stud removal tool. it's a circular item with a hole the middle that grips as you rotate it with a ratchet. that'll remove it. napa sells studs as well that will match up. To reinstall you're going to need a stud installation tool that napa should have. DO NOT USE THE REMOVAL TOOL TO REINSTALL. The removal tool grips the threads on the stud as it removes it and chews the threads up, you don't want that on the new stud!