Just got an Arc welder. I was wondering a few things.

An arc welder, so I understand, is essentially a huge ground loop/short that heats the wire and thus it fuses to the base. Because its like a big electrical short, does that mean I shouldn't or can't weld on the car? For instance... the exhaust hangers? Could I weld an Exhaust hanger to the car or what i need to disconnect everything electrical?

My other big BIG BIG question is... could I weld a bracket to my block? Obviously I don't want to penetrate the block, but it's an arc welder and it beads... I have an M50B25 and want to weld 2 steel "sleeves" if you will so I can bolt a bracket to them. I think the block is Iron, will this work? Will i blow the car up? What would I do to go about this?