I don't remember the names of missions but the Triathalon mission is a Mori mission and I'm 99% sure you have to do a Tony mission then a Yusuf mission (both involving parachutes, naturally) to open the base jumping challenges.
It's actually 8 nightclub activities, not 6. I got a percentage bump for 6 but there are 2 more and you get even more percentage. After 8 though you just keep running around the club and you never get the call to actually go out and do mission-style stuff so you can still earn money there but once the 8 missions are exhausted it gets boring.
But yeah, 8.
Edit: the list is right, it's just that someone mentioned 6.
Great list, cheers! I may be nitpicking but there's one tiny error on your list Enjoii. Getting the Gold Super Drop Diamond unlocked doesn't require you to complete the whole story. Completing every mission for Yusuf does the trick.