I don't think it will be possible to use the credit toward a dining plan, but you will probably be able to modify your package to have a dining plan instead. No one has done it before because this is all new territory.
It will likely revert to the way it was before park reservations were in place (pre-Covid). For Rise of the Resistance, you had to have scanned into the park to get a VQ spot.
This is not true. It's for almost all ticket-holders. You choose your starting date for multi-day tickets (this determines the price of the ticket.) This is on the Disney website:
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