Aren't you supposed to place the apostrophe after the S in cases of this?

When you're saying something belongs to a plural noun, aren't you supposed to put a single apostrophe after the S, and not another S after? For instance, if you were saying something belonged to the kids, you'd say, "The kids' object" instead of "The kid's object" or "The kids's object" Another question rolled into this one, if there's a restaurant named after someone, like James, would you call the restaurant, phonetically, "James," or "Jameses"? I ask because of a grammatical debate with a friend.