when calculating NPV what figure should I use as cash flows?

Question

Do I use revenues or cash inflows minus outflows (expenses, taxes etc).

Answer 1

Cashflow should be used (including invesment costs as well as expenses/tax etc as you mention).

If I recall correctly (dredging back through my memory of long ago finance courses) you can value a company on say, the value of its assets, OR its discounted future cashflows (NPV) but not both.