Zen Cart customization - date and time

Hello, We are modifying a customized Zen Cart shopping cart for a company that delivers lunch orders to businesses locally. There are 2 major customizations that we need done to the site. 1. Since there will only be a fixed number of items prepared for each day, my client would like to have the option to set a fixed number of items available for “today?? whatever the current date is. Orders are only taken for that day until 2:30, after 2:30 orders for that day will not be available, but people still need to be able to order for following days. Sometime between 2:30 pm and midnight, the number of items available for the next day will be updated. On the next day the number of items that will be available will be the number that has been updated. 2. When the user gets to the first page of the checkout, the user selects the date for delivery and the time of delivery. We need to have today’s date be the default that shows up for the date until 2:30 pm at which time the date for earliest delivery will be the next business day (Monday ??" Friday) No items will be delivered on weekend. The calendar on the site is already set to update each day, but we need the time availablity to update as well on the dropdown depending on what time of day it is. Please see the attached document for more specifics and email me if you have any questions. Thank you, Michael