my garage is 24x40 and use a propane heater bout 80k btu. 8 foot high bay's with another 4ft ceiling thats open. takes bout 20 minutes to warm it up... i like tim's idea of the used oil burner.. u can advertise on craigslist for pick up of oil.. just get a 275 gal tank... as for lighting, my garage has 3 switchs, front middle and back lighting. turn on what i need. i also put in outlets where the lights are for ease of removal of lite if needed.
in floor heat is nice if u leave it one.. concrete takes tooooo long to heat if u use it a few times a wk