Charter Checkout

I require a shopping cart for my website. The website has been built but is missing this element. The business in a yacht charter company. I require an online booking system, including the calander, availability (live info), checkout (I use paypal and can add that), blocked dates after a deposit or full payment is successfuly made, full price payment if booking is less than 56 days from the chosen start date, a deposit of 3 varying percentages of the full price if more than 56 days. There are 3 products of 1 day, 4 day and 7 day. There are 3 rates for each, High, Mid and Low Season, (totaling 9 products. I need to be able to add a peak season if I desire. I need to add discounts and special offers. I require notification by email of bookings and the ability to cancel, change or manage the bookings from admin. the product needs to be a simple intergration within my current script.