You will have 9 nights of the dining plan, as the plans are based on nights of your stay, not days.
The credits will be available from the moment you finish checking in until midnight following check out. These credits will be pooled and accessible from any KTTW card attached to the room, and since they are pooled, you may use them in any order and combination (up to the limit shown on your card, which reflects the group makeup for the room) you wish.