There are no water taxis from YC to DTD. I think you are thinking of POR and POFQ.
You have tons of options within walking and boating distance including all of the restaurants at YC/BC, BWI, Swan/Dolphin, EP and DHS. Just this year, we have had luck walking up and being seated quickly at Capt. Grille (lunch), Fresh (lunch), Kimono's (2 dinners) and Big River Grille (lunch). We have also gotten last minute reservations at Il Mulino and bluezoo. If you want to eat at a Swan/Dolphin restaurant, you are better off calling them directly than going on the WDW site. I think you will find there is still availability at most of the resort restaurants. If you want to venture into EP, Rose and Crown, Monsieur Paul and Chefs de France are very close to the IG entrance, so you won't have to walk far.