What @mmascari said. You can have multiple systems in the home without them interfering with each other.
I don't believe Alexa will talk to multiple homes at the same time. There may be some skill you can add to Alexa but I haven't seen it yet.
Formatting has been weird for some time now. However, the best programmers in Upper Bucks County are on the case.
IFTTT should work but I found it very clumsy and not very intuitive.
My invite to the ranch seems to have gotten lost. Can you send it again??