Khaos work just about anywhere. They come in 2 compounds, white is medium and blue is hard. The harder the surface, the harder compound or you will wear them out fast.
I run the V2 Turtle Clutch setup. They are tough and last. Watch DDM as they have them on sale about every 2 months. There are other makers but I can only speak for the Turtle as that is all I have ran.
Use the Yellow Hostile Zero Growth Foams in the rear. I run stock molded foams up front.
Is your car an HPI? This will matter for what braces you want to update.
Best place for a lot of good info is 1/5 scale oval racers on Facebook. Lots of great people their with good info.
Not sure if a stock 26 will hang with modded motors. I run all OBR engines. Fast, reliable and the best service in the business. Again, that's my opinion as I have not ran any other engines.
Any other questions, feel free to ask and get ready to have a fricken blast racing these big badass fast cars.