I'm thinking of setting up one (or more) of these at a remote location. There is power, but no phone line / internet connection. I was thinking of using a WiFi router with a SIM card slot as a mobile internet connection.

Q.1 Can anyone tell me what the expected daily data usage figures would be? Examples, a) if I didn't view any recordings, and b) if I viewed 1 hour live stream?

Q.2 Is it an "always on" connection to the server, or only when I open the app? 

I don't mind if it has a small amount of constant data transfer to a server (for pinging and update purposes, etc.), but if it's constantly streaming video without actually opening the feed, then it would probably use too much data for my budget. Hence, I'd need to have an idea of what to expect before buying a 4G router and data SIM card. 

Thanks in advance.