Agreeing with spicycat.

The OKW pool had a recently completed renovation which added a slide. Even before the slide, as spicycat posted, it was a pool with a lot of activity, noise and stimulation (my DD did not like to go in that pool because there were a lot of kids doing cannonballs, splashing, etc). With the slide, they will also have a lifeguards, but he/she will more be watching the slide.
The quiet pools at OKW are generally quiet and your DD would probably have an easier time there (you might actually have the pool mostly to yourselves). She would actually be able to swim at one of the quiet pools (as opposed to maybe being too overwhelmed by the activity at the main pool.
Some of the handicapped rooms have tubs with grab bars, others have roll in showers. Requesting a room with a tub is better than requesting not to have a handicapped room. When you check in, before you leave the check in point, they will show you what building it is on the map. You can ask then if there is a tub, what floor it's on, etc. The only buildings wwith elevators are those in the 60s.
For the questions about BCV. We have stayed at both BCV and BWV. One thing to be aware of is that if your room is not near the elevators, you will have a very long walk (some of it may be in the opposite direction you need to go when you get down, so there will be backtracking) to get to the elevators. I would not recommend either resort for someone with mobility problems/limitations unless they have a wheelchair/
ecv/special needs stroller for that reason.
Besides the feature pool, both resorts also have a nice, quiet pool you can use. SAB is an awesome pool, but it's sort of like a series of pools and channels, all connected together. Much more like a mini water park than a usual pool. It would not be a good pool for someone who might wander. Each pool area has more than one place you can get out of the pool and the landscaping hides the seating areas from each other. There are also points where you can exit directly onto the walkway that goes along the water side of the Boardwalk area. If you choose to go to BCV, I'd probably plan to spend more time at the quiet pool.
The main pool at BWV is more "pool-like" and would be easier to keep track of someone. The feature at BW is a slide with a large clown face. Some kids (adults too) just don't like that clown face. If your DD has any fears about clowns, that might be a pool to avoid.