Would the hitman be allowed to throw a grenade the mayors defense force?
Why would we have the granades if you weren't allowed to use them? Basically most People just throw 3 granades into ones home and run off, that is not allowed. But if you actually intend to kill the bastards then you should be allowed. But watch out, the admins might get the wrong impression in some situations.
Let's say I only killed the mayor, now the SAS/SWAT is behind me. Am I allowed to kill them to escape?
If you managed to kill the Mayor, there is 1. A high chance you are wanted for murdering the Mayor 2. A high chance you hit the swat/sas and are now wanted 3. The SWAT/SAS saw you, or atleast they will be searching. In any way, they are now going to kill/arrest you. So what do you do you say? Well standing off to 4 swat/sas or even 2 would be a bad 1st Choice, but if you had to then ofc go Ahead and shoot. But you should rather run like fuck, just saying.
Now let's say that the mayor is alone, but I don't have guns. Would I be allowed to use my car to crash him to death?
No....