First of all Captain please add some detail to what you are writing in the Topic almost all of your Suggestions are named 'Suggestion' it's hard to know which one is which.
Ok for the 1st one: Knife is super buggy and will screw things up, if you played GTA SA you will know you can insta kill anyone with a stealth knife kill.
In case of knife just add a pool cue.
2nd Suggestion: I do feel that securities and cops should have a separate chat, because it becomes confusing if the cops are actually responding to the backup/demands of president not.
And another thing, usually there are cops who want to suggest president something but the president doesn't know who the hell is he a security or cop because he can't stop to scroll through the Tab cmd. So in that regard yes this will be useful.
But this also has a chance to divert more from the gamemode and ruin teamwork more as people will simply use that cop exclusive chat for those wars and camping shiz,and also have the president writing extra cmds to chat with different people and wasting time which he shouldn't.
Imo every team member should be aware what the hell is his teammate is doing and the usual teamchat is good for that.