These idea's sound great but like I stated before, you'll want to read into the auto-x rules and guidelines to see what kind of modifications are/aren't allowed per class and what class you'd get put in. You may end up running against much faster and better cars.
And IMO, S2 Pro II coils are garbage for competitive racing. If you want something competitive, Koni/GC with custom spring rates. And you'll want something on the stiffer side if you want better handling. AFAIK, most, if not all, aftermarket springs and coilovers are setup so the fronts are stiffer than the rear which allows for more understeer. Higher spring rates in the rear than front allows for more oversteer. You either want to find a good balance or know how to control oversteer and get better spring rates.