Also, any changes, special room requests or adding the dining plan have to be done through the owner you rented from. Dining plans must be paid in full at the time that they are added to the reservation because that's the way that DVC works. Basically, they control the reservation until you check in.
You will have all of the advantages that any Disney resort guest gets (like EMH, access to the resort's theme pool, ADRs at 180+10, FP+ at 60 days prior to arrival, MBs) but none of the benefits that DVC members have (such as member discounts or events or Top of the World Lounge).
I believe they have to setup Magical Express for you because that is through the DVC portal if I recall correctly. Theres no harm in calling Magical Express though with your confirmation number and trying to set it up over the phone.