My wife and I usually only spend 3 hours at AK and see everything that we want to see and ride everything we want to ride. We hit the Safari first, walk through and see the gorillas (her favorite) and ride EE in the first hour and a half. The rest of the time is leisurely spent walking around. Not much going on at AK for us. Epcot on the other hand... We spend days there with the shops, food, few rides, etc..
As for the bus to HS... I would recommend taking the bus to Yacht/Beach club and walking to HS. It is a pretty quick process. If that is a burden, take a bus to the AKL and pick up a bus to HS there as the ride from AK to AKL isn't that long. The only problem is if you get to AKL and a bus has just left you may be waiting an extra 20 minutes or so.