they're 12mm nuts I beleive, possibly 10mm. (its been a few weeks since i took mine off) and i dunno about the pitch
get some silly putty, or bubble gum, and press it to one side of one of the studs. Then take it to the hardware store and match the thread iprint with the right bolt, then find the nut fr that bolt. My grandpa used to do that all the time. He used silly putty because he could make the mold, then put it in the little egg, and not have to worry about the imprint gettin messed up
goodluck
