Not OP, but I do all those things at a company with 4 engineers. I have only met a couple (as in 2 or 3) engineers that I estimate would be capable of doing most of those things, but it's not impossible.
And regarding 3: both, of course. But he'll probably care more about users in day to day work, as those are more directly relevant to his goals (making a good product).
And regarding 3: both, of course. But he'll probably care more about users in day to day work, as those are more directly relevant to his goals (making a good product).