Shane, I have been studying water-based finishes and have seen rave reviews about General Finishes water-based finishes from a number of places. I found several demonstration videos on youTube and wood whisperer.
Jesus, I construct a temporary paint booth in my garage using 1 1/2" schedule 40 PVC. I use 90 degree elbows for the corners and "T" fittings for the risers. I cut the wall frame pieces to 10' lenghts and the riser pieces to 8'. The connections are simply press-fit together so the whole thing can be disassembled. When the frame is assembled, it creates a frame that is about 10' wide x 10' long x 8' wide. I cover the "ceiling" with clear plastic sheeting that comes in rolls from one of the "big box" stores and attach it with blue tape. I then wrap the walls of the frame with the plastic sheeting and attach it with blue tape.
The floor of the paint booth is covered with scribing felt purchased from a local flooring company. It comes in 100' rolls, 36" wide. Roll it out on the floor and tape the seems together. The scribing felt helps absorb the paint overspray so you don't track much out of the booth.
The whole system is modular. If you need a bigger booth, get some more "T" fittings and make the booth 10' x 20', or 10' x 30', or 20' x 20', whatever meets your need.
I have sprayed Ben Moore Satin Impervo on painted cabinets and interior doors with a Graco airless and polyurethane (both oil-based and water-based) with a Wagner FineCoat 2000 (an older unit much like the Earlex 5000 or the little unit Rockler sells). I always wear a 3M respirator, cloth painter's hood, heavy rubber chemical gloves from Lowes, hospital-type booties over my shoes with a paint-dedicated long sleeve T-shirt and jeans. The only paint material I ever get on me is the bit of overspray that lands around my eyes. A little (very little) petroleum jelly around the eyes before painting makes for easy clean up when you're done.
Spraying enamel, poly, or water-based, and dressed in proper clothing and respirator, I have never found the need for exhaust ventilation from the booth. If you're taking air out of the booth, you risk bringing dust and contaminants in. I would certainly imagine you would need carefully planned ventilation if you are spraying lacquer of something more volatile. [eek]
I leave the painted/finished pieces in the booth until they are dry so they don't pick up any dust. The airless pump and paint are positioned outside the booth so they're not in the way and making it easier to clean up without contaminating the fresh paint or finish.