I am a medical professional and a NOOB, and all available practice management softwares (that are any good) use either Windows 10 or 7. Security Risk Analyses require all users upgrade to 10. Clinical operatory computers can safely (I assume) run 10, seeing as they will only be able to access the server and never the web. Front desk as well as business computers require access to insurances so as to verify benefits for each patient, and so I am considering these be running Windows 7.1 That is, one LAN cable will connect to the database server and another to the firewall, which will run BSD (either UnTangle or pfSense).
Is this system feasible, or should I simply run everything on 7.1 and to hell with any security updates, OR, run Windows 10 but never allow any computer to access Microsoft, which I will assume I can do at the firewall level?
At home I run Linux, with 10 set aside ONLY for programs not available in Linux, and then on that OS I have nothing installed in terms of personal info.
Your thoughts, and I thank you in advance.

If you are a beginner I would go for Mint or Manjaro.