I'm sure you can bring your own pillows, but you will need extra suitcases in order to do that (unless you bring along an inflatable one, which I sometimes do). You can request extras from your cabin steward as well. Yes, one of your suitcases can be a garment bag.
As far as your cabin location, it looks pretty good. It is mostly amidships, so there should be less motion than if it were farther forward. Also, it's about midway down on the ship, again, less motion than on a top deck. Good for you for getting a window!
I find that being able to see the horizon is great if motion is a problem.
I can't answer to the parking situation or the odors; perhaps someone has been on Sovereign recently, and/or has driven to the port.