Does the gap at the bottom of the garage between the sheet rock and floor could be sealed with a foam sealer or would that create moisture to build up in my wall. I'm planning on sealing the gap and laying base boards at the bottom of the wall to create that finished look.

I wouldn't fill it with foam, instead we just add a 1/2 filler to keep the baseboard from kicking in, but as far as insulating it, not unless the rest of the walls are, there is no point