For shock towers, RPM all the way. You could go aluminum if you want too, but with me with bashing and racing it's RPM plastic, light and flexible. For shocks I use the TRX Big Bores, Traxxas GTRs and ProLine shocks are nice. I don't think you can turn a slash (off-road) into a drift car but we can always try it out.
You have to lower the suspension. What I would do is use some thick shock oil (for the street), lower the suspension with using less or no preload spacers (ride height), use some fuel line in the shocks to limit shock travel. Also adjust shock mounts on the suspension arms to the lowest setting (all the way out near the wheel, or close to it.
Now for steering, you want the maximum you can do. Not sure if they offer any angle kits or anything for the slash.