Not much if it’s set up in a standard way because each node will only communicate directly with the node it’s expecting too. The communications are secured with the other node’s public key.
Normally yes, if using an object. In this case, the integer types implement the Copy trait, so instead of actually having your first call to add1 take ownership of x, it will just operate on a copy of the value, so your second call will work too.
They probably need to do some type of multiplexing/sharing broadcast time because they're on a fixed frequency. More tags means each can broadcast less frequently. If you divide the single tag freq by 750 or 9000 you'll get the same results.
I was actually using Podsync for a while, but in order to have that convert the videos to MP3s you need to pay, whereas this is free. Podsync is much more polished though.
Seems like it’s often the side channels that get people, even when they apply best practices to the primary system. I would be interested to know how passwords got into a log entry though.
A lot of interesting work has been done by the Israeli hydroponics industry around water conservation like some of the stuff in this article (as they grow their food in very high temperatures).