brake fluid on engine oil is a good one!
gauges are good to monitor your car for anything that goes wrong
those would be the best ones i can think of! The rest (Suspension, tyres) arent necessary for a good day out at the track! especially if its your first
as long as you have tread left on your 16s than it should be fine...
is your engine still standard? if so, i doubt you even need a larger radiator =)