Installing different types of insulation for garage?

I asked somewhat about this before. But I need to understand a few things. First of all, is bat panel installation put up in 4x8 sheets on the studs like drywall, or is it cut and place between the 15 is 2x4 studs? Also, I was thinking of gettin paper-backed rolled insulation so I could just run it from top of wall to floor and staple to studs on each side.. any better ideas? Which is cheaper. thanks