Vincent:
First I would stay away from slotted head design and stick with phillips, gives you more grip and can still screw it down from a slight angle
Second don't use brass, too soft will shear in you plywood, Your link is for a #1 which are very small!!!
I have been buying a box of 100 #4 x3/4 and a box of #6x 5/8 for most of my things. from my local ACE hardware store, maybe about 5~6 bucks a box. ( don't even think it was that much )
They will fit tortoise machines and this clamps and terminal strips.
I would also recommend that you buy a small bag of assorted clamps, since you might need to group more wires every once in a while. .

like here for all the power lines coming and going