If you are leaving from Newark, NJ, you are right, the flight arrives about 11:10PM. That is how we fly, not much choice, only one flight a day from Newark to Aguadilla!. We will be doing exactly that same thing in less than one month. We rent our car before we go, and after we get our luggage we walk to the rental place, (most of them are right there in the airport, or if not, they shuttle you down the street to the rental agency). It takes about 1/2 hour to drive from Aguadilla to Rincon, and you really need a car. It is very safe at night, very little traffic on the road at that hour.
You will like the Lazy Parrot, it is though on top of 413, with limited view of the ocean, but a really neat place to stay. You will also want a car if you are planning on getting to the beach, that would be a very long walk!
We go to Rincon every year, so if you have more questions, just ask!