If you plan on shooting a couple of cars a year, do yourself a favor and BUY a fresh air set up, leave the home made idea to patio tables and basket ball back boards. Buy a quality factory tested fresh air unit. Autobodystore.com has a "Hobbyair" system for about $400.00.
Barry, I am sure you have found what "wax and grease remover" to use and how to be careful with it while sanding basecoats. But honestly, for a newbe, I think he should stick to water. There are a number of different wax and grease removers all the way from mild (mostly straight mineral spirits) up to some pretty agressive solvents that will attack an uncured (or for that matter if the base doesn't use a hardener it never cures, only "drys") base coat. Plus you run into the chance (opening a whole new window of failure) trapping solvents from the wax and grease remover in the base.
Grabbing the wrong wax and grease remover and then applying more base or clear over it before the solvents have completely flashed out could end up biting you in the butt.
Milo, Windex, again, stick to the tech sheets. Windex has dyes, ammonia, these are things you don't want to mix with your paint system.