its very easy to install motors. Just take out the two motor screws and the grub screw out of the pinion gear to take it off. then just do the opposite to get it back in
as for the e-firestorm, stock on a GOOD 7.2v ni-mh it will do 20-25mph. I would either get the battary chris suggested or an SPC ener-g 4600 6c, very good, strong, high capacity cells.
