@wint0178 I am trying to respond your queries to my best. You may have better approach then my response too.
I assume that, you are using MySensors hardware in your setup.
As you have your gateways in different locations, you can connect all your gateways with MQTT connection (I would recommend secure MQTT).
You have to run a MyController server for 24x7, so you can go with RPI, it will save lot of your electricity and space.
Ultimately, I need to give data access to the communities themselves through the dashboard and SMS or email notifications. I would also like to have remote access to the data, but this is slightly less critical.
With MyController you can configure Email and web-hook(you may use it for SMS), For now there is no role based access in MyController v2. In MyController all the metric data will be in influx database. So you may share the details with Grafana dashboard too. I think it has read only dashboard.