Wordpress Site Developer with advanced shop skills

We have site ( ---------- ) that was developed by someone who is just not available to complete it and we need someone to complete it and be available for ongoing maintenance, improvement and the creation of additional simple sites.

The main issue is this:
- Shop needs multiple online shops to service particular regions or countries, where visitors from this region are automatically diverted to so they don't see the pricing of the other regions.
- There needs to be a system where visitors may be issues manually (by our on the road consultants) a 'code' which allows them to create a user account on the site that has a specific role (determined by the code and which gives price by role pricing) AND identifies the consultant as well so all future sales of this visitor create commission for the consultant.
- The commission is to be the difference between the product price available to the consultant 'role' and the 'role' of the signed up visitor, and tracked in a system to be paid at a later time
- The code should be able to be entered on the product page to reveal the special price associated to the role that the code gives access to, without the need to create an account just yet.
- Each region shop needs its own payment system, so that in future different payment gateways can be used. Like different paypal accounts.

Thank you kindly.