WOW ... so many questions. Let's see what I can do here??
1. LLS: So sorry, but I really can't be the judge of what works for your budget. Most folks like that the Grand is closer to DL, but other people like that the DLH is more "Disney-ish". The Grand is more subtle with it's Disney theme and keeps more true to the Art and Crafts/Bungalow style. You will have to make this decision on your own. With regard to the pool... no, the pools are exclusive to each hotel. If you were to go to the GS Desk and ask nicely, they might be able to help you out. Generally, each hotel can only go to their pool and workout facility.
2. MLGGATOR: With regard to rooms being available early, it's much the same as a late check out. If the hotel is sold out, then every room that someone is checking in to, someone has to check out first. Unfortunately, not everyone sticks to the 11:00 check out time. Rooms are generally available after 3 pm. You can request an early check in, but again, it's subject to availability and if there are no rooms the night before (or no rooms of the type you have booked), then you will probably get into the room after 3 pm. I see folks all the time with kids sleeping on the sofa's in the Great Hall. Most kids are pretty flexible and would sleep standing up if they are tired enough (I know that I can). If the little one needs a nap and the room is not ready then let them rest in a quiet area near the firepalce and let the rest of your group go an enjoy DL. All of the pool rooms are great and most of them you can see DCA in the background, so it's a dual view.
3. Danauk: Correct, the Parkview Terrace is located on the 5th floor, near where you woul see the 5019 to 5016 rooms. On the other side of the rooms map is the meeting space map and it shows the Parkview Terrance. If the Craftsmans Club is full, you can always grab breakfast for snack and escape to a nice pool view terrace and get some sunshine.
Have a good day all and let me know if I can be of any further assistance.