Welcome,
Clara! So many Groupies will have more knowledge than me, but here are my initial thoughts. And feel free to ask as many questions as you wish and join in our discussions! We are family here.
The studio categories are pretty much the same--I believe there may be one or two HA units. You're right in that bus run times do vary, but over the years, WL has ranked highly in terms of busing. I think you'll be pleased, and keep in mind there is boat service to MK, as well, which is a great way to travel there and back. The boat wait times can be a little long if you just miss a boat, but plan accordingly, and you'll love them. I believe you are correct about the top floors, so I'd request lake view, near the elevator in your case, or if you don't mind a lower floor, simply say lake view, lower floor. As for noise at the resort, I've found it to be one of the quietest on property. Yes, the EWP does go off around 9 pm nightly, but it's not terribly loud in the rooms if you keep the balcony doors closed. If you're on the lovely woods view side, you won't even hear it most likely. The most noise is in the main lobby where the check in desk, Mercantile, and WCC are located. Beyond that, it's a quiet place, even the pools.
And welcome to you, as well,
yaksack! Yes, I believe recent reports are that Roaring Fork is now 24-hour; if I'm wrong, I'm sure someone will correct me soon!
Both of you have great trips!