There is no specific mileage interval to replace the CVT transmission fluid. Most people are replacing it at 60-80,000 kilometers.
If you use hi-octane fuel, you won't need a fuel injector cleaner. Unless you live far from any fuel station that sells hi-octane. Only a few of these octane boosters/fuel injector cleaners really work, depends on which one(s) you are buying. Even a 50:50 ratio of supreme/super with hi-octane works fine.
I have personally found hi-octane at PSO on Khayaban-e-Ittehad DHA, PSO Tauheed Commercial, PSO Glass Tower, pretty much all the time unless it has been finished.