Can you rent cabanas at the pool area or on the beach?
NO, you can't. There are none.
No, everything by the pool is on a first come first serve basis. You can rent an umbrella an chairs by the beach or you can bring your own.
No, cabanas are on a first-come basis. There are no cabanas on the beach at the Port Royal, but you can rent umbrellas, chairs and boogie boards on the beach.
The cabanas at the pool are free. We usually bring our own beach chair and umbrella to the beach. There are beach concession stands in Wildwood Crest where you can rent chairs, umbrellas, boogie boards (and possibly surfboards). I don't think there are beach cabanas for rent in Wildwood Crest, but they seem to be available in Cape May and Wildwood.
Get an answer from Port Royal Hotel staff and past guests.