This isn't a Dining Plan question, moving to the Restaurant Board.
Cost of DDE membership for one year for AP holders is $65. There is an extra charge for a second card.
They let you pick up a temporary card. The pickup was at Epcot Guest Services outside the park. There's now the ability to buy it at Guest Services in any park, I don't know if someone who has already signed up can pick up a card or a temporary card at any Guest Services. Best thing to do is call DDE and ask for current policy.