Longer wheel base general tends to push a little compared to the same set-up on a short wheelbase.
Damper tubes - thicker fluid results in slower transfer of weight yeilding a little less responsive / more forgiving car. I run IRS/Speedmerchant Thick in the 10.5/19 turn car. Around 25,000 diff fluid I think although I've never run diff fluid personally.
For 19t 4-cell I would start with the pink rears and purple or softer front. THe yellow and gray rears with that much horsepower will likely feel spongy and the rear may feel like it's wondering side to side as the sidewalls flex. I would start those tires at around a 1.75" rear dia and roll out at around 2" (may start low say 1.8 and work up to it if unsure on motor/battery quality). fronts I'd start around 1.67. If the track is high bite you may even want to start closer to 1.72"-1.62" RR-FT.
Set ride height around 3.5mm to 4.25mm depending on track bumbyness. To get for steering you can run the front a little (0.25mm) lower than the rear and vice-versa.
Good Luck