We split stay every year and love it. I do recommend though doing the moderate on the front half of the trip and deluxe on back end. Hard to leave a deluxe to go to a moderate.
We found it very easy. We did Pop & AKL. We got up took our stuff to Bell services, took the bus to AK left AK around 3 went to AKL our room was ready, called Bell services they brought our stuff up to the room.
I think with your combo I would do Epcot that day & then you could walk to the BC. We really enjoyed our split stay & would do it again.
You can purchase tickets at your first resort for the entire 6 or 7 days no problem. If you want to do a package that includes dining, then two separate packages (one at each resort) would be required.