I'd go chromOS for ost everyone, few users need more, those who do may apply for exceptions, Win, MacOS or Linux. A pain but it is where we are now, I belive Google restricts all Windows, at least they did. You get MacOS or their own Linux. Strange I have not heard of a security issue at Google for many years, coincidence? I think not. Personally I just use ChromeOS now and one big Linux box if needed. Although my ChromeOS devices all have Linux loaded.

+1 for Pandas awesome.

In addition to the shared view, Microsoft Live has shared doc libraries, among numerous other features, and is beta on Mesh services, Synch, file and desktop sharing,... with that set you can do about all you've asked, free.