So I've decided to go with the rez. on the outside of the plant chambers/buckets. How should I go about fixing the problem of draining used nutrients from the buckets holding the plants after being misted? Or will the roots soak all of that up?

The most I think I'll be spending money on is the PVC plumbing and the misters -- Should I go metal/brass construction or stay plastic?

What size Orifice should I be looking for for 1/2" piping and 400GPH?

Orbit Full Radius Nozzle Plastic Pop Up Sprinkler - 54027 at The Home Depot