Most people add remote starting systems to cars in northern states to warm them up in extreme cold weather so I'm assuming that you're doing this to cool it down before you get into it? If so, that might not be a really good idea as there's the possibility of problems such as the engine could overheat if it's extremely hot outside and the engine's idling long with the AC on as ACs best with the car moving so moving airflow can pass through the condensor and radiator.
The remote start alarm system won't effect your warranty in itself UNLESS the installer botches the wiring install and taps into the wrong wires, then that'd be his problem. I've seen Volvos with remote starting alarm systems but if your car already has a factory alarm system, that's dissabled so you're then paying for a feature that you already have with the exception that you remotely start the car and although novel, I'd bet that after a while you probably won't even use it. You might be better off by just leaving the windows opened a crack (if you're sure it won't rain and outside) and turning the AC on once inside the car. Just my $.02.

As for the wheels, your car has a much better ride with 16s vs 17s with low profile tires. Sure, you might think the 17s and low profile tires look cool but they ride terribly, too solid IMO and you'll feel every crack and tar strip on every road. Another bummer about low profile tires is that if you have one get low on air pressure, the wheel will be more easily damaged by a pothole and niether wheel or tires for that is cheap.