So will I be charged as soon as I reserve? What if I am planning on buying dining plan?
Yes - but once you obtain your package then call the Disney Dining line and they will credit your card. At least that is what a CM told me.
My understanding is that if you do not have a reservation with a DDP already in place, that you will be charged in full for the meal at time of booking. If you have a DDP in place, then it can be linked so that you do not have to pay at the time of booking.