Salted Shrimp are added to various dishes, such as lotus leaf wrapped sticky rice, braised items and stir fries. My aunt does this braised nappa cabbage with mung bean thread noodles and dried shrimp (amongst other things).
They are also really good in Green Papaya Salad. My mom used to cook with them a lot, at first they kind of weirded me out, but now I like them. I think you just add them in as is, no reconstituting necessary. Tip: good cat treat!