Hi Andrew,
In order to install Insights for ArcGIS, you first need a Base ArcGIS Enterprise Deployment.
Per our Installation Prerequisites, the hardware requirements for Insights are dependent on those of ArcGIS Enterprise's components. See the individual system requirements for each of the components here.
As for your second question.. On a single-machine deployment, you only need to run the setup once. In a distributed deployment of ArcGIS Enterprise, you'll need to have Insights installed on each Portal machine and each ArcGIS Server machine. When running the the setup program, it will detect whether Portal for ArcGIS or ArcGIS Server is installed on your machine, and then it will install the appropriate Insights feature.
Hope this helps!
Nathan
