It appears the SWCG is an upgraded cost to the quote which includes the inline chlorinator. You do not need both so you may get a small credit to remove the inline chlorinator.
I do not see the depth of the sundeck. You need to be aware of the depth relative to the height of the coping. If your sundeck has 6 inches of water depth, you need to add about 4-5 inches to top of coping which makes that first step from ground level to the sundeck about 10-11 inches. So there is a need for a hand rail for your mom. Also, if you go with a deeper sundeck, say 9 inches then that first step becomes 13-14 inches, then you may want to consider a small step between the coping and the sundeck. So just think through the step heights from the deck into the pool, even with a hand rail.
The 4-5-4 or 4-5.5-4 depth should be fine for floating around in the pool. Not sure if you have siblings with kids that may visit but you want to consider that as well. I would lean to a 5.5 depth over a 5.0