Triples: YES, As far as i know the 999 and the 1098 have the exact same offset (36mm) and width on the top triple just make sure the fork type fitted is the same. I´ve test fitted a 1098 topr triple to my 916. No issue, straight bolt on.
999 Front rotors: Yes, I think so.. Offset is the same, but I´m not sure they will actually bolt on the 999 wheels. Depends on if its an R or not. But stock 999 rotors should fit directly in the calipers.. Don´t fit the spacers when remounting the calipers.
Reservoirs: Absolutly.. just a question of mounting them.