I'll admit that I only read the first few pages of this thread, but I thought I may have something to contribute.
I'm 19. I run a successful Photography business. I have been professional since I was 15. Take it from me, find somebody to help you run your business, and treat them well! I don't know how different all this stuff is in America, but down here I had to get an ABN, Insurance, register everything, and probably a couple of more things that I didn't even pick up on. I'm struggling to pick it up, but god knows learning how to run a business, let alone a successful one, is bloody hard! I'm doing my best, but having a few learning disorders, it's proving especially complicated to me. This is where my mum come's in (ok, I must really sound like a kid right now, haha) - but she knows this stuff. She's good at this stuff, and she helps me whenever I have an issue. But it doesn't have to be a parent, it could be a friend, a teacher, a mates parent - anybody who you know well enough to ask for some help from. Maybe throw them a bit of coin in the process, so that they don't think that they're being used. But the simple truth of it is, that at this age, without dedicating the time and money to go do some classes in business school or wherever it is you learn this stuff, we can't be expected to know all the things that the older crew on this forum do.
I'm currently picking a lot of it up through watching my mum and reading up on it whenever I can, but i've been making an income from photography since I was 15 years old, and continue to do so successfully. I may not be the most business savvy person, but i'm good at what I do - and that is perform a photographic service. Now don't get the idea that I have everything done for me, trust me I don't - I merely have somebody on the sidelines to give me a push in the right direction when it comes to accounting or the legality of contracts etc. - thing's that I don't quite understand as well as I probably could. When it comes down to it, I deal with clients, I deal with the workload, I get myself work, and I sustain that work by providing quality photos. I don't think I could be where I am, though, without having somebody behind me occasionally yelling "What the **** are you doing? No, that's not how it works!".
So this is my advise to you, find somebody that you trust, who cares about you, who knows how accounting and business work. Ask them for help! It's the only way to get through without actually spending the time in some form of a school learning this stuff.