DVC is Disney's version of a timeshare. So if you rent a reservation, you'd be either from a member for a lesser price or directly from Disney at the standard rack rate. Rack rate is rather high. From a member is less expensive. But you don't get cancellation policies like you get from Disney and you are dealing directly with the member. Disney isn't involved in any way.
You have no control over the reservation until the moment you check in. If you want the dining plan or Magical Express, the member has to add it for you. You can't call to confirm the reservation, but usually the member will forward a copy of the confirmation sheet to you if you want one.