Welcome!
If the rear tyre is also a 2012 then it's essential you replace it regardless of the tread left. Tyres age and a rear puncture on a M3W can be serious.
The Urban Cooling kit helps lower the engine temp when running and is a good thing to do regardless of the climate.
Add some form of derestricted exhaust - either by drilling out a baffle (bafflectomy) or for example Morgan Stage 1 / Garage56. This will improve the engine breathing and transform the car.
The key thing is to use it and enjoy it
