Customise Interspire Shopping Cart

My client is a florist, and we have setup their shopping cart using Interspire Shopping Cart which they are very happy with. However, being a florist they have some specil things they need customised due to the nature of their business. When people checkout, we need them to be able to have a field that people can type the message to go on the card. We also need them to be able to select a date from a calendar when their order should be delivered if they are pre-ordering a bouquet. Therefore, we need to add 2 custom fields (card message and date to deliver) into the checkout process? We also want to force people to select both a billing and delivery address (remove the tick box that says they are both the same)? Finally, can the credit card details, and all notes etc be printed on the invoice? Particularly the invoice which is printed from the admin area as my client would use this as an order sheet with all the info for that order.