Insurance Fraud is fixed too, you cant just slam into cars head on. What you have to do now is basically run to an adrenaline spot, but near a highway, so big trucks and shit appear a lot. From here, just jump then crumple into them, chances are you will get smacked into the sky, and you can try to aim yourself into more cars. When you get adrenaline boost you can run infinitely for a period of time, and when time runs out, the adrenaline meter acts as your last few seconds you have. Once I figured this out, everything was cake.
As for races, they are all fixed and varied, the car races you can use any car, but its better to just use whatever they set you up with.
Drug Trafficking is also WAY easier, as the driver can ACTUALLY SHOOT BACK