Sorry I'm only seeing your question now. We booked quite late on so when we enquired as to changing room it was too late. From speaking to others who had stayed previously best to avoid disappointment and book early to get the room you want.
not sure, we pre-paid and had a first floor pool / part sea view that we really nice but my sister had a room looking onto the smaller pool that was nice too
There isn't much of a sea view to be honest, just a small view between two adjacent buildings. If you want a pool view you may be able to ask at reception when you get there but of course that will only be possible if there are available rooms.
Get an answer from Las Vegas Hotel staff and past guests.