Hi Vincent!
You get dining credits for each night of your package. Since you're staying for five nights, you will get five "days" worth of dining. From your question I'm assuming that you have the deluxe dining plan?
If you have the deluxe dining plan, each person in your party gets three credits a day which can be used for any combination of quick or table service meals. With this plan each person will have a total of 15 meal credits and 10 snack credits. Your group's total would be 60 meal credits and 40 snack credits.
You can use the credits on your departure day. They will expire at midnight on the day you check out. The amount of gratuity you would need will depend on where you plan to eat and what you order. I think that a budget of $400 would be plenty for five days. If you would like to get a closer estimate you could check out the menus of the places you wish to dine at
www.allears.net . (From the home page, click on "Dining" at the top of the page and then "The Menus" on the left side.) When you look over the menus you can get an idea of what each meal may cost you,a nd then you can budget for 15-20% of the total plus a little extra for your gratuity.
I hope this helps! Please let me know if I can assist you further!