Nice strategy. I’m eager to try this out.
Would anyone care to recommend a piece of software that will allow me to build maps showing relationships? Something akin to a mindmap with nodes and a web of interconnections. I’d like to build a map of businesses and relationships in my industry. Something I can add to over many years.
It's what mathematicians[0] and programmers[1] refers to as a graph. Traditionally you would use http://graphviz.org/ and its many derivatives, which meets your long-term-stable criteria. These days if you want clicky web GUI you can use a bunch of javascript-ports, eg. https://sketchviz.com/new or https://github.com/jwilber/roughViz ... avoid valuing presentation over content, though.
[0] https://en.wikipedia.org/wiki/Graph_(discrete_mathematics) [1] https://en.wikipedia.org/wiki/Graph_(abstract_data_type)