Sorry to hear about your dad. I'm praying for a quick and easy recovery.
I do quite a few ADA showers in the remodels that I do for clients. From what you have said, it sounds like you have a solid plan. Some of my clients what to use chairs that they can remove, others want something built into the shower. Just be sure to block the framing for grab bars everywhere. I've put them vertical on either side of the shower handle, so they are right in front, and I've put them horizontal all the way around the shower. I would buy them now, so you know where to put your blocking when you are framing. I found the best options on Amazon, but the box stores have plenty to chose from. Some people are particular on how thick they are, so be sure to have them grip it before you install it.
Plan on two shower valves. One for the regular shower head and the other for the flexible shower head. A few people have done the combo units, but nobody likes them. Be sure to put the valve and handles where they can be reached without having to get wet.
There is no reason for a glass door on a walk in, ADA shower. It's just something extra to clean that costs a bunch of money.
Here are a few pictures of a bathroom that I finished last week. It had a bathtub in it that she was afraid to use. She is elderly and she was afraid of tripping over the tub, so she used the hall bathroom instead of this one. I'm not a fan of the shower head, but it's what she wanted. Same thing with the 12x24 fake marble wall tile. It's all the fashion right now, so I'm doing a lot of it, or white subway. Seems that's what everyone wants right now. The inside of the shower is 3 1/2 inches by 7 feet. In my opinion, this is just about the perfect size for a shower. Most of my clients want the little corner seat on the other side, farther away from the shower head. It's where the ladies put their feet when shaving. My wife uses ours to store towels.
Here is a built in seat that they wanted because of knee surgeries. They wanted two valves for the rain head, and then the hand held shower.
This client wanted the handle close to the door, but the shower was longer where the shower head is. With PEX, it's super easy to put the shower head anywhere.
This client has a collection of at least 20 different shower heads. He's sort of crazy on finding the right one!!! He also wanted lots of options while taking a shower.