Q2: You can. Hiding the update that contains the nagware worked for me[1]. You should allow windows to install other updates (fixing bugs, security risks, ect.).
Q3: The 31 day deadline is to free-up space once a user has settled down with Win10. Advanced users can work around this [2].
I can’t answer all these questions unfortunately! Q1 and Q5 are fairly subjective - I think it's up to you to form your own opinion on those.
[1] http://www.howtogeek.com/218856/how-do-you-disable-the-get-w... [2] http://www.thewindowsclub.com/rollback-windows-10-after-30-d...