Just a little clarification -- the op requested what's a walk away. Knotts Berry Farm is a little more than a walk away from DL and DCA!
As for restaurants just outside the park -- if you go through the Grand Californian to the front, then go out to the street and turn LEFT, you can walk down to the corner of Katella and Disney Way. There are 2 restaurants near that corner -- Coco's (closest to the Best Western) and one that was, at one time,called Tiffy's. (This was 4 years ago, don't know if it's still there, though daughter assures me that Coco's is still there.)
My husband's and my very favorite DL restaurant is Blue Bayou. It's not that the food is all that wonderful (it's good but nothing to rave about). It's the ambiance of sitting right next to the waters of POTC. Call early, get a reservation, and then state that you're willing to wait for a table on the water (if that's true). It's worth the wait. You can also see onto the balconies of Club 33 from many of the tables in BB.
To me, 7 days would be a little much. Back in 2008, we opted for a "one tank car trip". It included 3 days of DL/DCA (and we'd never been to DCA at that point). By the third day, we were opting for the shows and anything where we didn't have to walk a lot.
Donna