I believe that the old moniker "If you don't value your time why should anyone else" rings true here. Giving it away for free may indeed give you great experience *if* you can allow people to let you into the fold. Consider startups that *can* take on interns but don't simply because its a chore to see a good example of this in motion. If you're not creating value in yourself you're certainly not going to translate that value to your clients, customers etc..

The best piece of advice I ever got was to swim with the sharks. Go to pitch competitions, conferences, clubs and other events where they will be at. As stated above, don't pitch them but instead play the role of a colleague in the startup atmosphere.

I think that the answer is dependent on the level of technical talent that is already on-board. If you have an engineering focused squad, you can get away with rudimentary understanding. To your description a "non-technical CEO" is just that. Of course, whenever there is a gap in the team, it is generally the CEO's job to wear different types of hats as the weather changes. One of those hats may be a hacker.