Metering power consumption for three houses


This is my very first post so sorry if not following any of its rules or something. I am facing a project of metering power consumption on three different houses. Know how to do it with z-wave sensors and a z-wave gateway but was looking into a way of making all information available in a self-hosted “cloud”. Nevertheless, as new as I am to homeassistant, I am not sure what do I need and if ir can be done. I understand I need:

  • A server to run homeassistant on
  • Sensors at each house
  • A gateway at each house
  • A lot of configuration

My questions are:

  1. What z-wave gateway (good quality and memory to store a lot of sensors reads if connection drops) can you recommend to use with homeassistant? I have been having a look at the web to no avail. Not sure what do the gateway needs to be able to interact with homeassistan.
  2. How fast does a realworld database grow over time? I know, everycase is different but would love to hear your experiences (number of sensors, reads per minute… etc…).
  3. Is this system error proof? I mean, stored data on the gateway during a power outage is loaded back to our cloud whenever the lost connection is restablished?
  4. Can homeassistan manage different entities (in this case, houses) together and assign them to users who can have different right access privileges?

I am totally new to homeassistant and don’t even know where is what…

Thanks in advance,