I don't know for you but, by default, all our ISP box here broadcast an "open" SSID that allows any customers of this ISP to login with their ISP credentials on the ISP box around them (except if the customers switch off this function). That allow a customer with a dead box or in travel to still have internet. (traffic is of course segregated).
So if you know the ISP brand via the IP range and find a isolated home with this provider ssid visible, you found the address of the IP. Again that work only with low number of houses or not often use ISP.
Connect for me is not connected like a logon but more in term of network connection (pinged).
Good question. Let me check that.
Well following their documentation, it's a distinct IP in a specific IP range.
Good!