Add Holidays to jQuery's datepicker on Shopify Cart Page

General information for the website: Grocery Delivery Company with a shopify Store
Num. of web pages/modules: 1
The task is to do the following:

1. Add Holidays(black-out dates/non sleectable dates) to jQuery's datepicker in a Shopify Basket Page so that the shop can have control what dates are not available for selection by the customer.
2. Make it copmulsory for the customer to choose a date before continuing through the checkout process.
3. Adjust the CSS so that the date picker is aligned on the Right hand side of the cart page


Here's the page I'm referring to. As you can see the jQuery date picker is already there with weekends blacked-out.

https://freshideadirect.myshopify.com/cart/
Extra notes:

Here's some notes from someone else whose completed the tasks:
Balcout dates:
https://ecommerce.shopify.com/c/ecommerce-design/t/shopify-datepicker-exclude-days-solved-112234
Make it copmulsory:
https://ecommerce.shopify.com/c/ecommerce-design/t/mandatory-date-picker-279086