I'd agree with all previous comments. My experience (and I'm also a technical co-founder) is that one of the biggest hurdles you will most likely face is keeping them engaged, motivated and continually producing quality work.
Obviously if you're paying them this is less of a problem, but the thing with a lot of engineers is, if they are good they have lots of options in what they work on. You might be able to snag a quality engineer and keep them in for a few months, but building a product is no walk in the park. Something new comes up for them you could loose them easily if you can't consistently keep them engaged.
So yes. I do think it's important to find people that are into the space but also find people that are into you and the team. There is nothing worse then working with someone whom you don't jive with on a personal level especially in a startup environment.
Lastly, I would say your next hurdle will be vetting them from a technical standpoint. You said you and your co-founder are non tech people. It's going to be really important that you get a product out that does not need to be rebuilt in six months. It surly won't have everything it needs out of the gate but if it can be built upon easily once you start getting feedback this will be key.
I'd say you should find a bunch of people and take your time to make a decision, maybe build out a feature or work on a "test" project for a 4-8 weeks while you're at it crank up the stress levels a bit and see how they react. You'll thank yourself in the long run.