Wordpress Website edits - theme and plugins

We have a Wordpress WooCommerce website: We need for 3 following issues resolved. Website Troubleshooting: 1. Coupon redeem page We have a coupon redeem page – The customer enters a coupon code they have – this coupon is associated with a product and redirects the customer to the checkout page with the product in the basket and the coupon applied. This was built using ajax I think – and is no longer working. We need someone to fix it. 2. Checkout page We have an age verification box at checkout that requires people to enter a date of birth. It currently is in the wrong format – MM-DD-YYYY, Needs to be DD/MM/YYYY There is also has a Japanese logo on the dropdown datepicker, we need to remove this. (If there is a better plugin for this function that would be great – otherwise a custom coded solution). See image attached. This is the plugin we are using: [login to view URL] 3. Age Gateway – Mobile number keyboard On age gateway – make keyboard numbers show up for mobile users (see image) OR On mobile – turn the date entry form into a Yes/No button All changes made should be saved in our child theme in a way that is future proofed against updating of plugins or themes. We are happy to provide further details upon request. We will ask you to confirm you are capable of completing all tasks before we offer you the job. ***Please bid an accurate amount for this project.****