I have the Tornado BB (which is a powered down older version of the s30) and I love it. There are a few things that you might as well buy in bulk along with the car thogh. I will list those later.
how do you upgrade the sh .18 to a sh .28?
...You can't. The .18 is plenty big enough, and the .28 is HUMOUNGUOS. No chance of it fitting
Second, how do you tune in the motors?
Thats a bit harder to answer. There is no exact formula for tuning, but you want the car to run between 200 and 290 degrees farenheight (to avoid damage) As long as the motor stays within those tolerances, and is not too lean, you can tune for performance as much as you'd like. If you had no idea about what i just said watch this
video (actually, watch it anyway)
What other than extra glow plugs, nitro, and a starter kit will I need?
(3 packs), wheel hubs
(1 pack), Fail Safe
(just one. It seems expensive but it pays for itself later on), 47 tooth gear
(get 5 or 6), 2nd gear spur gear
(just one),Temp Sensor
You cannot use the Volcano's wheels without a decrease in performance, because that will dramatically change the gear ratio, and the stock tires work well on gravel, dirt, and pavement.
video on break in tips.