I have managed and done lots of similar projects. Designs is done by my friend, a professional designer, I make it go live and work as you wish. Examples of his and my work are available and will send on request.
I can cover all issues of such a project: domain(s), DNS, server settings, hosting settings, SSL, implementing payments via PayPal, etc.
No open source CMS is used but a tailored web site is made using my skeleton CMS that can implement all wishes. If it is technically possible it can be implemented and later expanded any way you like. SEO is implemented in the CMS and results achieved mostly depend on content and wished page layout.
As I have lots of experience I will probably propose suggestions on how to achieve goals you wish or do things better, more user-friendly, etc.
Happy Easter and best regards,
Tomislav Crnicki
Croatia, Europe