First of all, you have Hatzlacha Supermarket on Flushing avenue between Franklin & Skillman. It’s nice and they have a fleishig takeout section as well.
I think there’s also a grocery on Bedford ave. bet Flushing and Park called “chestnut” (I might be wrong about the name)
about Shopping, you have S&W clothing and shoes on Wallabout between Bedford and Lee Avenue, and in General most stores are on Lee Avenue. 5 min. by car. Even if you’re walking- Williamsburg isn’t that big, so if you have time I’d recommend going up a few blocks and checking out Lee Avenue.