Yes, a warped head could let coolant get into the bore for the head bolt. If the proper mix of antifreeze is used, the bolt shouldn't rust, however. If somebody ran straight water for a while, the bolt could have started rusting if it was wet with coolant.
Hard valve seats- - - -unless the seats need changing for some other reason, the risks outweigh the benefits, and unless you're pulling hard with a max payload all the time or running on Propane instead of gasoline, hard seats aren't necessary. There's the possibility that if a seat is installed in an even slightly oversize counterbore, it can come adrift and trash a piston and/or a cylinder head. I would have to have a LOT of faith in my machinist to even consider letting him install valve seats of any kind, but Stellite seats in particular are very problematic. Get the head shaved until it's level, do a regular valve job, and drive on! It costs less that way, also.
Jerry
