Build your Slow Stick absolutely stock to start out with, worry about upgrades later. I fly on the stock 400c brushed motor and a 2200mah lipo, no extra reinforcement on the wings, only the included carbon fiber spars for the leading and trailing edge...it'll fly and carry it's weight around just fine. When you start adding cameras and extra weight you can modify then. The first upgrades I'd suggest is the one piece carbon fiber fuselage boom and balsa tail group from radicalrc.com.
Oh, for sure do the prop adapter...this is a free upgrade if you use a servo control horn and get a bag of the little girls ponytail rubber bands (they're about the size of braces rubber bands)