Customising quotation email

Good Morning,

We have developed our website using Woocommerce.
After selecting items and going to the checkout page we reach https://www.libromania.cl/checkout/

After submitting the information, an e-mail is sent with the list of the items selected.
I’d like to customise this e-mail using information of the checkout page. In detail I’d like to:
1.- add an expected shipping cost based on the location of the customer (there are 16 defined regions, each of them have an extra % of the total order as shipping cost)
2.- add a combo selection in the checkout page for the customer to select one of the 16 available regions and pass this result to be used in the e-mail creation to set the right extra % to add
3.- add a discount to the quotation based on the total amount quoted

I’d really appreciate you can confiorm how to do this. Please confirm where should modify the code in order to change the information showed in the quotation e-mail sent and some guidelines about how to do these three points.

Many thanks
Arcturus

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