You could get a taxi from Grand Case to Orient Beach relatively easy. About $15 USD, I believe. Definitely too far to walk.

There are several restaurants open in the Grand Case area including Bistro Caraibes, Rainbow Cafe, Spiga and several others. Not all have bounced back from Hurricane Irma, however. You can check out other posts on this message board for additional restaurants or search online.

If you want to stay in Grand Case there's a lovely little hotel called LePetit Hotel further west on the same road. Never stayed here, but we did sort of take a mini tour a few years ago. Run by a very nice couple (Remy and ?). I know they are open for business. Or, you could stay in Orient Village. Quite sure the La Plantation hotel is open, and was always priced reasonably in the past. Esmeralda is also open in the same area, and is actually closer to Orient Beach. But, it's likely more expensive this time of year. Finally, the Oyster Bay Beach Resort (OBBR) is just south on the Dutch side and is priced similar to La Plantation. There are some nice restaurants nearby, but you'd have to check to see which ones have reopened after Irma. Good luck with your search!