Develop a membership site for online learning programs

We are working on a new membership site for an online weight loss program. The idea is that customers sign up for a "starter course" which is an online learning programm consisting of videos, emails, articles and downloads (delivered within the membership plattform, usually over 4 days) At the end of the starter course, the customer can sign up to join the "club" which gives them additional features and also continued access to all the materials from the course. During the club membership (recurring monthly, quarterly or yearly payments) the clients have access to new materials (videos, articles, etc posted weekly) but can also buy upgrades to other course modules. As long as they remain a club member, they have access to the materials they bought in the different packages. Additional feature: we would like for the client to go through a questionnaire at the beginning to get a better picture of their individual situation and then suggest which modules are most suitable for them - and then lead them through an upsell process fro these modules. Important issues: 1) The front end of this site is in German. 2) We are looking for a site that is fully integrated with a payment solution (including billing and all transactional email; payment, invoicing as well as refunds and credit notes should be automated). 3) Must be able to handle european accounting requirements, which are: - show prices including VAT (not sales tax on top of price); calculate a different VAT on the invoice for each country (e.g. if we sell to a customer from Germany, VAT is 19%, for an Austrian client it is 20% - VAT has to be shown as part of the final price, so a price of EUR 100 already includes EUR 16,67 VAT for Austria or EUR 15,96 for Germany, respectively) - send an automatic invoice with a unique invoice number for each order (and be able to download or print all the invoices for a certain period for accounting purposes) - issue a credit note with a unique number when the client cancels the subscription and request a refund; issue refund automatically (and be able to download those for accounting) 3) handle european payment requirements: direct debit, wire transfer and credit cards 4) we currently use infusionsoft for our email marketing and zendesk for customer support. Ideally, this would be integrated into the new site. When you apply for the job, please answer the following questions: 1) Which membership site software would you recommend using and why? 2) If necessary (which we assume), which shop software would you recommend using and why?