I'll try to help based on our experience there on the 18th.
1) Yes, V&A accept the TiW card in the dining room for the standard menu only. If you are dining at the chef's table or ask for the chef's table menu while being seated in the dining room the TiW discount will not apply.
2) You just give them the card when they present the bill and you're ready to pay. There is no need to tell them in advance that you have a discount card.
3) As far as I know they do accept Disney Reward Dollars as payment towards the final bill. You can certainly call and ask them in order to verify.
4) When you make the dinner reservation they will ask about allergies and preferences at that time. They will also call you back about 10 days before your actual reservation to confirm these things and to make sure there isn't anything they may have missed.