Yes, you just need to have the owner you rented from make the DDP request for you at least 5 days ahead of the trip. That's what MS says anyway. In reality, we were able to add it just 24 hours ahead. FYI, tickets and dining plan are not connected for DVC. Most units have cooking facilities, so DP is an add on.
Yes, you can add the dining plan when staying in any DVC accomodation, studio included, on points. D&B was referring to the fact that members can use DVC points to stay at other non-DVC Disney hotels (think Grand Floridian, Port Orleans...any regular WDW hotel) and I guess you can't add the DDP when staying at these resorts on DVC points. If you are staying in one of the DVC resorts you need not worry.