That beauty pageant job sounds dodgy as all hell, RUN AWAY FAST!!! And in fairness, there are some honest nightclub owners/promoters out there, I'm sure, hopefully including these guys.
As for how to run a company, well that's quite a big ask for a forum post. For any job where you have upfront costs (or guaranteed costs or commitments you're making), the client should give you money upfront. My terms of business say 50% upfront, and 25% during production and 25% on delivery. Your mileage may vary (as does mine, job-by-job, to be fair - for corporate clients I front all the costs and get paid 6-12 weeks later, so build in a cost of credit!)
Even if you can't afford a lawyer, make sure you have every job spec written up and agreed and signed on paper before you start, or it becomes an all-you-can-eat video buffet. The purpose of the spec is to include what *is* and *isn't* included. For instance for the weddings, maybe you provide one master DVD, but copies are charged extra at $10/each. DVD cover art - included/excluded? Number of cameras/operators? Length of the vid? How long you'll be on-site? Who pays for your lunch? EVERYTHING - get it on paper, get it agreed, then and only then can you know when the job is finished (you can effectively tick the boxes on the list on the paper), and so when you should get paid, and how much.
Quoting for a job - tricky one. They want you as cheap as possible, you want to make a profit of course. It's all about who bears the *RISK* in the project.
*If you have carte blanche to work as many hours as you like at $x per hour, to hire in equipment on their bill, to hire in staff, to pay post-houses, to let them change their minds as long as they pay for the time and costs, they are bearing the risk. If something goes wrong, or they change their minds, great, you get more hours and paid more.
*If you quote a fixed price for the job, you have the potential to organise yourself efficiently (workflows!), and make a better profit. But if something goes wrong, you bear the costs of remedial action, the risk is on you, so cost it accordingly to give yourself wriggle room.
*If you quote a fixed price for a core set of activities, but in your (paper! always on paper!) agreement you set out that the client pays for any changes of mind they have at $x per day + costs. You share the risk, so if you balls up, you cover the costs, but they can't change their minds every 10 mins and hope to get more 'stuff' for free.
*If they offer you a 'Not to exceed' deal, where they pay you a day rate and costs up to a certain ceiling, run a mile. Never touch one of these jobs. If you work smart, you get no benefit, if there's a problem, you suffer for it. You bear all the risk, with no wriggle room and no mitigation. I took one of these jobs once, never ever again. I was young, dumb, and hadn't realised the implications. This one tip could save you thousands, learn from my mistake!
How much to charge? Well, look at your costs (include transport, hotels, food, hires, crew, stock, insurance, etc), look at the competition, and position yourself in the market where you want to be. Premium-end hiring in top-notch kit and crew? Cheap? etc., and price accordingly. Remember there's a lot of competition at both ends, so you can't necessarily compete on price alone. Maybe compete on convenience, flexibility, find a niche market you can service expertly (like free-running, small bands, college proms, whatever), etc.
For me, I have a mixture of clients and work - some is insultingly cheap (if I've nothing else on), some free, some premium, but I don't tell each market about the others. The cheap guys expect premium quality, or the premium guys want cheaper shoots - keep them separate.
There's a hell of a lot to do to run a business. I wish you much luck! And perhaps, just perhaps, one day you'll be in a position where you'll can give me a job - don't forget me