2. When you look at photos, be aware that there are accessible studios which do not have roll in showers. For some reason, I always get assigned a handicapped accessible room although I never requested it, don't need it and don't want it. (If the handicapped accessible rooms are not used for people who need it, then anybody can get assigned to anyone.) In the bathroom that I had, the bathtub/shower combo, sink and toilet were all in one room together. The bathroom was huge, but there were no shelves on which to place your toiletries. But a bathroom with a roll in shower might be different. Also, this was before the last refurb, so things might have changed.
3 For comparison purposes: pre-COVID, I stayed at BoardWalk Villas. The fitness center there has locker rooms. The ladies' locker rooms has lockers, 2 showers, 2 toilet stalls and 2 sinks. But the situation has always been different at Beach Club. IIRC, the showers were supposed to be for people using the spa, not for people using the fitness center. Eventually people were banned from using the showers unless they had an appointment at the spa. Fairly recently they added shower rooms out by the pool. I don't know if there were lockers near those showers. There have always been lockers in the Stormalong Bay pool area. I think there may outdoor showers near the pool where you can rinse off the chlorine.