This is the drill/tap I used to thread some cylinder locks I had. It is a #6/32 tap. Anything harder than the material you are threading will work. So if the core is bronze or brass (soft), any steel tap will be fine.
Sure! The case comes with some extra hardware. Standard ATX standoff and hard drive screw spec is 6-32 which is what I used. There should also be some extra 6-32 screws in with the case, also some extra M3 screws. Either basic hand-tap will work...