Awesome!
I like little details in the missions, so here a few idea's for little details.
Redneck- If they give a weapon for the mission, make it molotov and shotgun only.
- Cars are always parked wrong and not all cars start/work. Some cars are already damaged and smoking.
- All radio stations in this area are blocked with home-made radio blocker, but own radio with country music works!

(maybe make zaibatsu mission that the blocker needs to be taken down)
- Oil slicks on the roads.
- Little groups of gangmembers smoking on the side of the road.
- Strange places (hidden) are guns/weapons.
- Amount of ammunition of weapons in the fort is not always the same and often low.

- Hardly any cop in the area/fort, but just on the outside of the fence a lot.
Zaibatsu- All very clean and working properly.
- Cars parked perfect.
- Guns are on clear/perfect position and always same amount of ammunition.
- Lots of cops in the area. Hmm, or not... not sure.
Scientists- Cars sometimes with no reason explode or start fire. Experimental engines go broken, something like that as reason.
- Some gangmembers suddenly go crazy with electrofingers or go running wild.
- Mines on the sidewalks for no clear reason. Failed experiments?
- RC-cars passing by.
- Some very unique car designs on the road near the base. It are test cars. Perhaps some can go very fast, but start smoking if you do. lol
etc. I can go on for a while.
Some mission idea's:- '
Drunk Silence'. You play for zaibatsu and carry a silence machine gun. the task is to infiltrate the redneck base and steal the secret liquor recipe without them knowing it. you need to be not detected and shoot two correct bullets within 2-3 sec else the guard is not death and the alarm goes off.
- '
Police Blocker'. The redneck screwed up and the cops are coming in big numbers. to protect the fort you need to make a wall of cars in front of the gate. you need to use for this zaibatsu cars so the police thinks zaibatsu is helping them, so steal a lot of them. problem is that zaibatsu don't like that and will remove the cars if you don't do it within a certain time.
- '
Noisy drugs'. The scientists have developed a new drugs and the whole city is addicted. the drugs makes people go naked. lol. anyway, the scientist are not happy and stopped the delivery of the drugs, but the people are "stuck" in the drugs, the only way to get them out is a big loud sound. your task is to get a wanted level with lots of police cars so it makes a lot of noise. than it's the task to run atleast a few minutes in the city with the cops on your tail to get people out of the drugs. lol, long mission description. haha
//edit. if you like the mission idea's, I can perhaps think of more. if one mission is not clear, please ask, I'm not good at explaining my idea in english and perhaps forgotten important parts.