basic Tstats do not argue. Suggest Radio Thermostat CT100/Zwave or CT50/Wifi has good support in ST, not supercheap or basic but less than $100 each. I think CT50 has the advantage of independent remote management - when you see all 3 Tstats in the native phone app, I bet most people like it pretty good uh-huh.
Filtrete 3M-50 is the same as RT CT50, and this devicetype also works with RT CT80, you just don’t get remote humidity.
Zwave probly ok as-is, or plug-in extender.
use a mechanical strap-on Tstat instead, and monitor it with Zwave sensor if you want. It is pointlessly complicated to require your Zwave to operate your temperature safety control.
1 - I use the CT50, it has place for 2 modules wifi and zwave I use it with wifi in ST. I tried it with z-wave and it was too erratic. Been using it for 5+ years works good.
2- You shouldn’t have any issue as long as there is no interference in the way.
3- You can do this but most temp sensors are a pain to get accurate and report enough. Do some research on the one you’re buying to see if you can calibrate it and how it works.
4- I don’t have any suggestions but you can find a list of compatible cameras with the ST ecosystem at http://www.smartthings.com/compatible-products
5- I’m sure there is a smart app that does this.
For standard zwave you may have some issues with the distance and weather. A safe bet would be to use at least 1 plug-in zwave plus device in each building near an outside wall. zwave plus has MUCH better range and can still repeat standard zwave signals. Keep in mind that shooting 30ft outside on a clear day is not the same as shooting 30ft when its raining. Water does not play well with RF (zwave, zigbee, wifi, bluetooth).