Hmm Spinners can be found by Proline, velocity rims and the spinners just mount on them . Pretty pricey. Then the BEST RC cage is the RC-solutions cage for it.
RC-solutions has the best cage, I would stay away from the spinners, the spinners are Al and they are to light to get spinning nicely, IMO a big wast of $$$ but if you are making a show truck they would be coolish.
One of the best and cheapest ways to increase handling out of the box is upgrading to firmer tire foams like the trinity low roll foams. Panther and proline also have firmer foam options. They cost about $20 for all four wheels.
remoter? You mean receiver? or Transmitter? If it is the stock Savage radio, I think you should be able to just upgradethe reverse and servo. No need to get a really expensive servo. It is not used as often as the throttle and steering. Ask your LHS and see if you cvan get a decent one for it. no more then 20 bux