Welcome to the forum. If you put your location in your profile it will help others give you better answers in terms of where to source new studs. It also gives context to your posts later on other subjects.
Yes, you will need to replace the exhaust gaskets if you separate the headers from the engine. And it will be a lot easier to replace the studs if you remove the exhaust pipes first.
The exhaust gasket is: Gasket, Exhaust Pipe, P/N 4FM-14613-00-00 (2 needed)
The nuts are: Nut, P/N 90179-08410-00 (you need 4)
The studs are: Bolt, Stud, P/N 95612-08625-00
None of these are very expensive from US vendors like
www.PartShark.com, but not knowing where in the world you are, I can't offer a good source for you. The studs and nuts can also be sourced from a high quality hardware or automotive source. They are fairly normal metric fasteners if you know the correct size. I do not have a Super Ten at this time, so can't measure them.
I would suggest you clean the exhaust nuts/stud ends as Chris has suggested first. Then soak them in penetrating oil from an aerosol can and let them sit for an hour before attempting to loosen the nuts. Most likely the nuts will come off fine with this process. Don't get in a hurry and try not to apply excessive force, but sometimes things do break. Hope for the best, prepare for the worst.
Once you have the header/exhaust pipes off, you should be able to soak the threads to the cylinder head with penetrating oil and let them sit for an hour or so. then apply some heat from a propane torch to the base of each stud. You're not trying to melt anything! Just get some heat to the stud to loosen the thread locking compound. You don't want the studs glowing or anything, just moderately hot.
At this point, the double nut technique that Jiq1969 suggested is an excellent method to start with. If one won't move, stop, re-apply penetrating oil and some low heat and let sit again before trying once more.
Once you have the studs out, if you are going to try to source replacement studs and nuts locally, take a stud and nut with you to the hardware or automotive store and you should have no problem finding matching replacements. Tell whom ever is helping you that you are using them for exhaust manifold studs so they know what to best offer you.
When you install the new studs, use the same double nut technique to thread them in tight.