Springs and Grandstand are your best bets. The only issues concerning her needs relate to whether she's using a manual or power chair. If it's a manual that can be folded up and she prefers to walk some on her crutches, I'd ask for Springs. The reason is that things are mostly level to the pool with only one side having a sloped walkway to Artist Palette. It's all a gentle incline but can be a bit of an issue with some manual wheelchair users.
Springs is also the last stop on the bus route. If your friend has a power chair (or one that can't be folded), she may run into the issue of the bus being full. (Each bus has two wheelchair/
scooter spots.)
In a powerchair situation, I'd recommend the Grandstand section. It is the first on the bus route so always empty. There's also an easy walkway to the Carriage House which I found shorter than my Springs unit last December, although it does involve an incline as well. If she can manage to get in the pool with a few steps, the Grandstand buildings are also much closer to the pool.
I used the main pool the most this last trip and stayed in the Grandstand building nearest the bus stop. It was wonderful. The pool's zero entry eliminated all my mobility issues (I have severe arthritis). There's also the pool lift chair (ask the lifeguards to bring it out for you) and a pool wheelchair to wheel right into the pool. I didn't use the lift for the hot tub. I'm not even aware it works there. Wish I'd thought to ask now. I love a nice hot soak. In any case, the pool's accessibility was so great that I found myself passing up park days just to go swimming. (Who needs to watch Illuminations for the 15th time when you can spend your last hours floating along?)
Don't fret about the layout of SSR. There are tons of scenic walkways, benches and ways or getting around. We loved our strolls around the resort so much we'd just get the bus driver to drop us off somewhere else and wander back to our room. It only feels big when you are in a hurry or it is during the hot midday sun. 1-4pm. That's when you just want to grab your suit and hit the pool.