Head gasket?

do you have to changed the headbolt to changed the head gasket?Head gasket?why change it, just use some sodium silicate block sealer :)
Head gasket?
It depends on certain engines. So, yes. Best to get a repair manual for that vehicle, and it should tell you that warning there.
Head gasket?
no
Some require it, and some do not. A lot of the head bolts are called %26quot;torque to yield%26quot; bolts, which are made to stretch and create sort of a tugging action on the head to the block. These bolts will not spring back into place, and are ruined once removed. Putting these bolts back in will cause more problems than you want to think about...

Even if the bolts are reuseable bolts, there is a lot of heat which has a potential of expanding the metal...

in my opinion, I would change the bolts to save you time, money, and headaches!
No, but you might have to have the head ground if it has been overheated.
mark d nailed it. check your manual. some cars reuse, some replace. typically older cars reuse, and smaller imports replace but that is just a rule of thumb. if you have a reuse car, make sure you wirebrush the threads of the bolts, and tap the holes in the block so that you dont get a false torque reading from all the rust and gunk on the bolts. and dont forget sealant on any head bolt that penetrates a water jacket in the block.
As previously mentioned, some do and some don't. The mentioned %26quot;torque to yield%26quot; type do for the reason that Mark D mentioned about the stretching. Later Ford 4 cylinder engines require replacing cylinder head bolts, like the Escort engines and such. Most of the 6 cylinders and V8s do not. Here is an easy way to tell if it is a torque to yield type: look at the head of the bolt. If it is the regular 6 sided type, then most likely it does not need to be replaced. If it has 12 points or looks like it takes an allen wrench to take it out, it will be a torque to yeild type.
If the torque specs. are torque-to-yield, YES.