What is the best way to remove a stripped head bolt?

[hughet]

I was moving along on my 603 head removal until I stripped out one of the head bolts. Maybe it was damaged or I wasn't careful enough, but those 12 point "triple square" bolts seem to be pretty fragile. Anyway I am stuck in the mud until I can get this one out.
Is there some kind of extractor to use or should I just get a 3/16 drill bit and drill down into the cap of the bolt until it takes the top off?
Also are the bolts made of hardened steel and do I need to use a special bit?
The only other thing I need to do to lift the head off the car is to remove the connection on the right side where the heater pipe goes into the head. I turned that large connector about 3 times and now it is getting harder to turn. Is there some kind of trick to it?