Most of these ideas have been addressed.
Having that many preset options on the server would cause further server problems, that's why it wasn't included in Feral Heart.
Prey has been stated as something that's going to be released, at some point. Possibly. Though I believe that will only jack up the server more.
Super jump, I actually like that idea.
Items wouldn't be dropped, seeing as everyone can have the same items.
Collisions over characters would prove both difficult to program and a bother to other players. I for one like being able to be obnoxious and sit on my friends.
People should simply follow the rules, collision box wouldn't be necessary.