Verdict
Most years at No 1 : Impossible
Oldest in Top 10: Possible if he wanted it but highly unlikely that he does.
Oldest in Top 100: Almost certain if he wanted it but highly unlikely that he does.
Oldest GS winner of all time: Impossible
Oldest Aus Open winner: Extremely unlikely but not impossible
Oldest US Open winner: Extremely unlikely
Most singles titles: Very possible if he was willing to do anything to get it but suspect he would consider vulturing 250s as beneath his dignity. So unlikely.
Most after 30: Possible but with the reservations of above
Most singles matches won: Almost certain if he wanted it but with same reservations.
0:2 in sets: Unlikely given age
5 set matches won: As above
Most singles finals played: Possible
Singles matches played: This one seems quite likely.
Oldest singles title winner: No
Oldest match winner: Almost certainly achievable but he won't play that long.