We are finishing the attic of our 1931 brick 4-square home (it has a slate roof). I looked behind the kneewall and ceiling and there is no insulation. The house does not have any soffit or attic vents.

Do I need to be concerned with insulating the attic?

Will insulating the attic cause moisture buildup behind the walls?

Will I need to install soffit vents to prevent moisture buildup since originally the house does not have soffit venting?

Should I use faced or unfaced insulation?

And what is this 1 inch minimum air space requirement that I keep reading about?