Let the dealer do your spark plugs, and brake flush. Proper gap is important, and flushing out the system can be problematic if you don’t know what you’re doing. Cabin air filter, typically behind glove box, engine air filter, in the engine compartment. A rotation consists of putting your front tires in the rear and vice versa, simple but tasking. Oil changes are easy, Subarus typically have 10,000 bolts and clips to remove though (exaggeration). Make sure you get the proper oil viscosity, fill amount, and oil filter, which can be found on amsoil.com