Protection For This Circuit
Diodes will protect your driver and MC from back EMF.
Your driver has 30Amp peak and 10Amp rated, and your motors require 8+2.5=10.5 Amp, maybe it is not necessary to place output capacitors, but I would place some value around 47uF for starting (depending of what kind of output you have).
Try to connect GND from motors close to the battery input (to define path to the circuit wide from driver and MCU as much as possible).