Custom digital products on Woocommerce

I haven’t found a plugin that can do what I need:
1) Outside WordPress, the customer configures a custom downloadable data product.
2) Also outside WordPress, the price of the downloadable product changes depending on the number of rows the downloadable data product has.
3) Now WordPress: Customer places his/her product order using some embedded cart button on the non-Wordpress site (I need to be able to provide a key and a price to the button).
4) Goes through Woocommerce checkout process, pays and sends confirmation linked to key to my non-Wordpress site.
5) My non-Wordpress site provides a downloadable link to Woocommerce with the key.
6) Customer receives from Woocommerce a downloadable product link by email.

You might wonder: This is so custom, why don’t you do it outside Woocommerce.

The answer is I want to have all the rest of the stuff around Woocommerce and WordPress.

Thanks!