Definitely replace the exhaust gaskets, try not to force the bolts or they'll spin out, but they are also easily replaceable as long as you don't break them!
You may not even see a gasket when you take off the header as it's been crushed over time, but it's there, you may have to peel it out with a sharp pointy device to ensure you don't have 2 gaskets.
My kickstand has never loosened, I wonder if you have the original nut in there. Possibly a nylon nut with locking washer? Will take a look when I get home later today.