The airport likely will not be very busy, but that's not really going to affect your timing too much. As noted, the DME luggage transfer service stops running at 10:00 p.m., so you will have to claim your own bags. When we have stayed at the Poly it has been the first stop on the bus, but at that hour they could have all kinds of non-standard groupings as passengers will be few and far between, so it's difficult to predict what will happen. The last time we got in late (not quite as late as you will), we wound up being the only people on a full-sized bus and had a private motor coach ride direct to the Poly.
I would hope that your bus will get you to your resort within 90 minutes of you landing, but it could take longer depending on how much time it takes to get your bags and other factors.