Yes, I'm generally looking for someone who can do all of those things (though I don't work in DSP, so it's not an exact mapping). I would say that at least part of #3 is coding. If you're actually defining code layout etc., you are basically coding. If you dig deep enough here, you can probably rule out the vast majority of people who can't do #4. I still think it's a more efficient use of time to just ask them to do a bit of coding, though. Then I have certainty on the question rather than an implicit answer.