I recommend this as well. You may have some imperfections in your head and/or block that are causing the leak. Also, I don't think you're supposed to use sealant on the head gasket. You are supposed to replace the head bolts when you remove them because they streach and can cause the torque specs to change.

Here's what I suggest:
head
get it resurfaced
get an OEM gasket
get a good torque wrench and book so you know what order and what torque to tighten them
get a new set of bolts

overheating
I think you should flush the system with some of that flush stuff you can get at the auto store
Use that and see if it still overheats; if it does, turn your original thermostat backwards. This will allow the fluid to flow all the time. If you still overheat, I have no idea what the problem could be other than a bad fan switch.

Hope it helps man, I feel your pain.