On 4, what MQTT broker(s) would you recommend? I’be been reading up a bit on different alternatives[0] for something lightweight with not too many dependencies to run clustered/HA and haven’t figured out which one to try yet.
As for android client, I recommend this[1] but it requires Tasker Autonotification plugin to display notifications.
[1]https://play.google.com/store/apps/details?id=in.dc297.mqttc...