Mats and liner you can worry about them later. You can save on installation labor if you have them installed now, like black grille, towing hitch or roof rails.
About car detailing, I recommend do it yourself, everything you need to know is on youtube/internet. I had a toyota before my x3, and I didn't bother to wash it myself. But I discovered that spending time washing my BMW is really an rewarding enjoyment, why pay someone else to do it. Plus, in my opinion no matter how good an auto detailer is, he will never be as careful and thorough as a passionate car owner.
Polishing is taking off a thin layer of your clear coat, I don't ( some people do) think thats needed for a brand new car. I recommend clay bar on day 1 and a good layer of carnauba wax. Wash and wax your car often can have better result than opti-coat.