headstuds are like the shaft section of a bolt, but they stick up out of the block and you lower the head down onto them, then add a nut to torque the head down.
the idea is they are re-usable multiple times, whereas your standard headbolt should only be used once (though many people re-use them) so they work out cheaper if you intend to take the head off multiple times to fiddle with things.
you could use whatever headgasket you liked, but i couldnt comment on their re-usability as i've never tried it myself
