Prestashop 1.7. - custom modules and modifications

I am looking for a programmer for long-term cooperation to create custom modules and make modifications to Prestashop 1.7.

For PS I mainly need:

- Adjust the order of order steps. Make an ideal four-step order process: 1) Shopping cart - 2) Shipping and payment selection - 3) Delivery and billing address - 4) Order check and confirmation
- Edit the management of product variants in the admin and add the necessary data to them (e.g. pairing codes..)
- Adjust product pricing in admin
- Connection to our invoicing and warehouse SW using XML or API
- Drawing availability of products from the supplier's feed
- Watchdog for unavailable products
- Add new shipping and payment features.
- Export of XML feeds for price comparators

and then fine-tune some details and errors. And more adjustments over time.
In the case of cooperation, I would describe the individual tasks in detail and specify the assignment.

Thank you!