As the subject says, I was closing the bleeder screw and the head sheared
right off.  Wasn't applying too much torque, but maybe it was because I had
done that in the past.  Anyway, the good news is that it was all coolant
coming out; I think it was adequately burped!

So.

(A) Time to get one of those screw extractor thingies I guess.

Recommendations on which kind/brand?  (I'm looking at

http://www.oreillyauto.com/site/c/detail/TTN0/16013/N0673.oap

because it says it's in stock and I'm trying to be done with this thing.)

More importantly, though, how am I going to get that extractor into the top
of the screw?  Bringing up

(B) Bentley 19.12 refers to "lowering" the radiator.  When it's in it's
"lowered" state will I be able to get at the screw, or am I going to have
to completely disconnect it?

(C) Does anyone know the specs on this bolt?  Does it need to be a certain
type of metal?  I would just order one but I'm trying to get this thing on
the road ASAP so I can check it out thoroughly for a longer drive.  It
would be nice to be able to just grab one from the hardware store if that's
possible.