This will probably get moved to the Occupancy Thread. Technically, the studio and one bedroom have a capacity of four, but MS is allowing people to bring along five (I think three are supposed to be kids) in the one bedroom, but not in the studio. Again, technically, you are only supposed to get four room keys for both of these villas, but they may give you five. If you plan to go to EMH, you will each need a room key to get your evening wristband or to enter the park in the morning.
You will have four bath towels, probably only two hand towels (maybe four) and probably four facecloths.
When you make your reservation they will ask for the names of all the guests. So, yes, they do know who is staying in the room. If you don't give them a name, that person will not get a room ID (room key).
It might be good to plan for your future when you may need a two bedroom instead of your present when you might be able to get by with a one bedroom.
In my opinion, OKW is the only one bedroom with enough room for five. The others are smaller. We had four of us (three adults and one kid) at SSR in October. We had tried to get a two bedroom, but just couldn't get one. It seemed very crowded with the sleeper sofa pulled out, my son on the floor, and all my SIL's luggage in the living room.
You might not have any problems with the one bedroom; this just gives you something to think about in making your decision.