OK, let's talk weapons!
What Rollcage is all about, is speed. Weapons should be oriented around speed - constructive speed and destructive speed. Whatever the weapons do, speed should be involved. Destructive effects should not, must not make my car slow to a halt, or freeze it in the air (like the stage 2 stasis beam) or do anything that breaks the adrenaline rush of going fast. My dream weapons for Grip would violently throw the car away in the direction of the impact (while inducing rotation and chaos, of course). Make the missiles a double-edge sword: Highly likely to make the opponent lose control, but has just the off chance to kick them over the finish line when used unwisely. Let the victim keep some momentum, so that a skilled player has a chance of recovering without even stopping.
Where I'm trying to go here: Remove the stuff that's not fun. The worst thing in Rollcage 1 and particularly 2, is having an unwanted weapon occupy a slot. Let me eject the weapon, maybe as a mine effect, or a minor explosion, instead having to watch the chain gun fire at nothing for 10 seconds before I can pick up another TURBO or ROCKET.
I voted for the driller missile, and that alone. The others seemed un-conductive to maintaining speed and fun. EMP disables the engine? No thanks! Let the EMP cause one of my weapons to fire at random instead. Kick me, throw me, blow me up, just don't slow me. That's why I hate Mario Kart.
There's a bunch of discussion on teleporting. For me it's simple: Keep the Wormhole from Rollcage 1. It was a brilliant weapon. Having it as a semi-physical object that homed in on the car ahead of you required a little skill, and made for some great fun. You coudl dodge it by driving up walls, causing it to explode behind you, giving you a little boost. If you got captured, you couldn't instantly fire a weapon, and the car ahead would keep control of your steering for a few seconds - effectively adding a whole layer of tactics. Occasionally, the wormhole would not work at all, just explode, giving you extra speed at the cost of control. Or you could shake it off by going slow and turning. Best of all was to fire a Wormhole and a Leader Seeker simultaneously - causing a massive explosion that lifted you up and threw you ahead.
By now it should be obvious I'm a hardcore Rollcage 1 fan, so let me just suggest something new: Two different types of shield. Kinetic shield (RC2 body-hugging graphics) protects you from impacts with other cars. Energy shield (RC1 bubble graphics) protects you from weapons. Using both causes them to annihilate and creates a massive explosion. Hitting an opponent using one, while you're using the other, creates a smaller blast, throwing you apart. Never mind Radius Bomb or Pulse Push or whatever. Just do this.
Also, allow more than two Leader Seekers to be in flight simultaneously.