You could use 6mm, 1/4", or 8mm.
Drill choice is a lot about personal preference, experience, and strategy. You could use, straight flutes, spiral up and down cutters, or a compression cutter. Is there anyone you can get to help you with it? Are you making it in a makerspace?
These videos might help
Although worth noting that neither of these videos understand the purpose of Up-cut drill bits. They are to be used in tandem with Down-cut bits as they stop tarot on the bottom side of the material when you cut through.
Good luck