Jessica:
One of my favorite websites to get exact travel times from the Disney resorts to the parks is
www.ourlaughingplace.com. They have a "Transport Wizard" down near the bottom of the page that allows you to enter in point A and point B and gives you the travel options (boat vs. bus) and travel times.
In my experience, from the Fort Wilderness Cabins, a lot depends on whether you are taking the internal buses at the camp ground or have a golf cart to get to the pier and Outpost Bus Station, as the Transport Wizard doesn't calculate the internal ride times.....just add on an additional 15 minutes or so for them.
Specifically, the bus rides from the fort to each of the parks vary from about 15 minutes to Epcot to 25 to 30 minutes to Animal Kingdom....From the pier, the boat ride to the Contemporary is about 15 minutes. If you want to go to the Polynesian from the fort, you'll need to take the same boat to the Contemporary and then hop on the monorail to get to the Polynesian (the next stop on the monorail).
Wishing y'all a magical vacation!
Whitney