Unless you seal your car in a glass bubble and extract the air, there's no way a paint finish will stay perfect... and that's if the paint is even perfect to begin with. I would say most dealership will do a "fine" job washing the car to give to you. At worst, you can examine the car before signing and refuse if it is unsatisfactory. Or ask that they cover the cost of a paint-correcting detail.
Unless it's pretty severe, any swirls and other paint markings can be corrected with some know-how and the correct tools. You can take it to a profesional detailer who will do a great job for a couple hundred bucks, or spend that or a little more and buy all the stuff yourself. (Orbital polisher, pads, and associated polishing and protectant products.)
Even if nobody touches the paint but you (or pro detailer), you'll need to polish the paint every year or so anyway. More if you drive a lot.
As for dealership decals and plate frames, my take is this: They are welcome to put them on my car if and only if they are willing to pay me a monthly fee to advertise for them. Other than that, if I like a dealership's service, I will recommend them of my own accord.