Your description of government's role is very close to mine, I'd just add (C) do what the private sector does obviously badly in our current society framework (like most infrastructure, energy, ..., long term stuff, where competition does not work).
Given your list of publication, I hope you'll write a diary about one of those topic here!
Agreed on (C).
Unfortunately, I have no special expertise to offer about these topics. I am no economist/sociologist even if sometimes I like to pretend otherwise.
