Hello,
1) For the cart page you need to create a new page named cart or whatever you want and add the following Shortcode inside the page and publish.
[woocommerce_cart]
2) For the Checkout Page you need to create a new page as well and add the following shortcode inside it and publish.
[woocommerce_checkout]
Then you need to add them as the pages from WooCommerce >> Settings >> Advanced.
Screenshot for Clarification: https://ibb.co/rx0LzN2
3) For the colors, provide some relevant screenshots to check it myself and help you out accordingly.
Regards.
Xtemos Studios.
.
