I built a site for a school to manage their alumni association. So it's a complete site with a dashboard that exists at say example.com where they can create new campaigns, add pictures, add news posts etc. After a while, some other schools also wanted the same portal as I built for the one school. I don't know how many more will want this kind of site, but many more will it seems. So instead of building out each site individually, I want to build a SaaS of sorts. So that each school can sign up and spin up it's own such alumni association site. All the portals will be accessible from one TLD, so the url will be something like example.com/school1 or school1.example.com.

I have never built something like this, so I have several questions:

1) I'm guessing I can use the site I have as a template to spin off new sites in the new SaaS?

2) What is the correct term for this multi-tenant setup so that I know how to speak when I ask questions or do consultations?

3) What resources can I use to learn to build such a multi-tenant infrastructure? I have not seen any literature on such indulgences. I'm looking for books, blog posts, tutorials etc on architecting such kind of software or something close.

4) What technologies am I looking at utilizing to build out such and what expertise should I be looking for? Is this what stuff like Docker/Kubernetes/containerization is used for in isolating stuff? Or I should be looking at something else?

5) What are some potential pitfalls and points of concern that are unique to this endeavor that I should keep in mind when planning this out?