Hi Becky,
We recently stayed in the 2100 loop of the
Cabins at Fort Wilderness with 4 of our children. I enjoyed that loop because it was secluded and nicely wooded. Some of the loops have been cleared and don't have as much of a "woodsy" feel to them. The 2500 and 2600 loops are located fairly close to one of the leisure pools. However to get to the main pool (with slide and play area), you'll want to take an Internal Shuttle from any of the Cabin loops.
If you are not renting a golf cart, you'll want to take the Internal Shuttle to get to the regular Park buses and boats. We tried walking from our Cabin once and quickly got on the next shuttle that came by. The Fort is very large and things are quite spread out. You'll be going to both ends of the Fort to get to different Parks. For example, for the boats to Magic Kingdom, you'll go to the Settlement Depot. For a bus to Animal Kingdom or Epcot, you'll go to the Outpost Depot. The Front Desk will provide you with a detailed transportation map upon check-in that will explain the bus system to you.
As far as requesting a specific loop, you can certainly add the request to your reservation. While this is never guaranteed, Disney does do their best to honor requests based on availability.
Hope this helps and please let me know if I can assist you further,
Kaylene