Alright, lets see.
The Seatbelt is for WalkFX, try the num keys (you may have to turn num lock on or off) or if those don't work, check your key configuration.
About the AI, it's possible a script error has occurred, please get a console report when you notice the AI not attacking.
About the bridge scrolling, you should have a mutator called: "Sneaker98's Bridge Menu Scroller" activate it.