ideas for insulating garage/wall ceiling covering

Maybe,just maybe,I'll actually get around to doing something...seeing as how I've only been here 20 years.Geez! Where does time go? The garage has trusses and I'd like to use rock wool insulation.Yes,I know i can Google it but I'd prefer ideas from people that have done this themselves. There is no storage in the ceiling so that will be closed off.The electrical will be moved outside the walls,ala European. I get the put the insulation between joists,what about above it?How do you lay it in with all the bracing? I need to picture how it's going to look before starting.(and that is probably another reason I never get things finished cause once I visualize it done,I'm done). How about covering for walls/ceiling? Drywall? Plywood? Metal? A friend did plywood but I'd want to coat it in fireproofing(?) paint. If drywall was used, I suppose taping is needed so it doesn't leak air? Metal would be cool BUT...Any ideas and PICTURES would be helpful. Of course,there is 20 plus years of accumulation that needs to be moved around to work any area at a time.Hmm,maybe I'd clean up a bit? Thanks for any ideas!Bob