Gasket only needs to be changed if its falling apart which it shouldn't be, when you put the gasket back in just cover it in vaseline and it'll be fine. When you take it off you'll have to loosen the mount on the front left hand corner of the block that is holding the EFI pipe in place and then just leaver off the rocker with a flat head screw driver and get your fingers under it when you can.
Make sure the HT leads are out of the way, the 2 breather pipes are off (one in between spark chamber 1 and 2 and one at the back of the rocker, think its called a PCV valve), The EFI bracket is loosened and the injecter lines that run along the back of the rocker are out of the way.
I used high temp paint on mine which you DO NOT need primer for.
Preperation should be as said above with wet dry paper and white spirit or something like that and then wash it in hot soapy water and make sure it is completely dry before spraying.
Even though i used high temp paint i dont think it's necessary and you could probably use normal car paint with primer.
Hope that helps
Christian