I'd be down for that. Although how would Jury Fury IL work? You would do it normally or instapass it?

I disagree with pre-made replays not being allowed. If you're allowed to set up your weapons like you want, and get car bombs set up like you want, why can't you set up a replay?

As for omf0 manipulation, I also disagree. Any sort of pre-mission setup should be allowed, and mission flag manipulation is allowed in every other IL (and is frequently abused to its full extent in SA). To ban duping, just say "It's not allowed to have the game run two mission scripts at the same time"

0. there should be mission ILs for SA and III too
1. i don't think millis are needed, it's fine if there are draws. this way, people won't go insane shaving off frames
2. when you skip the cutscene or when the cutscene starts. i prefer the skipping
3. "when the mission ends". if there are confusing missions, clarify it in the description individually
4. i don't really see why it shouldn't have an IL, worst case is that no one will run it

How about adding Taxi Driver, Paramedic, Pizza Boy, Firefighter and Vigilante?

RC missions + races also don't fall under your definition of what a mission is, but they exist in level-leaderboard already.