Don't mind at all. The bus trip to the MK from Pop is no more than 15 minutes, and its probably not even that long. The bus stop for Pop at the MK is the farthest away from the entrance, but its not bad.
It was hot. Temps were in the low 90s all week, and it was pretty humid, but definitely not unbearable. Just drink lots of water, and hit the inside attractions when you get too hot. Most everything at WDW has A/C, so you should be fine. Take sunscreen for sure though!
We usually don't do a real detailed itinerary when we go. We know what park we are going to on each given day, and we get there at rope drop, which really helps. We avoid the parks with extra magic hours, as these tend to be busier, and on days when Fantasmic is showing at the Studios, it will absolutely be busier than non fantasmic days. If you want to see it, just be prepared for the crowds. It may be a bit scary for your DD2 anyway, but it is a good show. We generally skip it now as we've seen it quite a few times.
Just make use of Fastpass if you need to for the big attractions. We really didn't need fastpass last week, but if its busy, use it for sure. You will definitely want to Fastpass Toy Story Mania at the studios, as it always has a line.
Pop was really cool, and I think your DDs will love it. Try to get in a building close to Classic Hall, as it is a big resort, and there are some rooms that are quite a walk from the bus stops. We had a blast, just can't believe how fast a week goes at WDW. Have fun, and if you need anything else, feel free to ask me.
Thank you so much for the info! I really appreciate it. We were going to skip Fantasmic, so I am glad to hear you suggest the same.
Thanks again!