The pro kit is prety much ready to go.

A few things I would do:

Buy the dace rear skid plate, the rear of the chassis gets beat up fast.
I would also buy normal shock dust boots, the Kyoshos work well. I am not a fan of the felt wipes they dont work well.

Other than the basics spares, like some shock parts (shafts, etc) and a set of arms and hub carriers you should be set.