I think racing is fine the way it is in PTP currently, but all your other suggestions I don't really like. If any of them are added, they should be controlled by admins, not by minimum player count. Racing and duels don't allow many players ignore the GM, while your other suggestions do. I think it would be better not to script events but instead to put in commands that let people opt into admin-controlled events. For example, a /joinevent command for a civilian to opt in, then admin commands like /massget, /massgive, /massspawnvehicle, /masshealth, etc. that perform their function for all the people who have done /joinevent (and haven't been removed from the event). It saves admins time over the current system and also allows for more flexible events.
Example:
Jonne does /createevent 30 (30 seconds to join).
Vishwas, YoMama, Ricky, Makaveli are all civilians who have done /joinevent.
Jonne does /massget to teleport all four civilians to his location, /massgodmode so they don't kill each other, then /massgive <grenade> 1000 to give all participants 1000 grenades.
Jonne does /massfreezecount, which freezes participants and starts a countdown, at the end of the countdown participants are unfrozen and godmode is removed.
Participants fight, etc...
Maybe there could also be a command to create teams, so you could have an event with some throwing grenades from a Rustler at others who are using rocket launchers to try to shoot them down, for example.
While I think this is a better idea than scripted events, I definitely don't think it should even be a priority if it's added at all. Races and duels are fine.