After you've filled in the blanks, you'll feel much more comfortable, and at that point make some hires to deal with those specific business areas, while still maintaining overall control. As others have said, you guys are doing something right or you wouldn't be in this position in the first place.
If I was over in SF, I'd love to help you out, but I'm based in Sydney.
Anyway, best of luck to you.
I don't have a company myself, but some people I know who do have had a lot of success linking up with the local university's Business programs (MBAs, or in my case a Master's in Management of Technology)... many professors have consultancy businesses on the side, and you can also draw on the students' abilities - for example, as a student, I got assigned to a 2M/year company, they gave us insider access and, with the teachers' guidance, we gave them a free consultancy.
I also recommend a Master's in Management (MOT or an MBA), running a company yourself you'll get a lot of value out of it. I see many California universities offer one (MOT or similar), maybe there's a graduate here on Hacker News who can recommend one.
Traditional "interview and put in place" hiring strategies are built around the needs of traditional large organisations with massive amounts of existing organisational momentum and plenty of time to recover from mistakes or retrain duff hires.
Small fast-moving companies don't have those advantages, and shouldn't hire that way. You're obviously innovative - don't forget to apply that creativity to your business processes.