Fix WooCommerce Checkout page possibly soon - functional fix and little aesthetic fix

Hi,
The project is about making changes on the Checkout Page of WooCommerce - WordPress based website, both mobile as desktop.

Currently Installed exterior plugins that need to stay (already bought, installed and configured) are 1) payU payment gateway (works ok)
2) WP Desk InPost integration - doesn't work well, especially on mobile

- A vital point is to obtain a checkout where the user experience is nice and flawless; this regards especially fixing the workflow of the WP Desk InPost plugin
- Speed optimization is key
- Working links to privacy policy (change link to page)
- little padding work between the points for a more clear interface
- Modify button color and font
- Boxes with inserted words validation + zip code format autocomplete
- One section which now is constantly open should be by default closed and open only when users clicks

We are open to using special plugins for checkout, as long as they will work properly together with the mentioned plugins above.

Timing is also relevant.
Thank you, best regards