imo yes. a 4x4 and about 480w true power draw of LED. how hot does the garage get? with LED and exhausting out a window you can pretty much keep a tent at the same temperature as the room its in even while lights are running. If you exhaust back into the garage eventually the lights will heat all the air in the room and the temps will rise. you would probably only need the AC with recirculating exhaust if the garage gets above 83-85F. Otherwise running exhaust direct to outdoors would be fine.
I have a few tents in my house and I keep them exhausting directly out a window as often as I can. when it gets really hot I close the windows, run the house AC and let the tents exhaust circulate in the house like you said, and the power bill goes way up.
yes. LED are pretty expensive. $300 could be done but it would be DIY, def not anything good ready to hang at that price.