Having studied entrepreneurship as a master-degree, I learned that business-plans are important for the entrepreneur to verbalise what he is doing. If he can't do that in a plan, can he do it to outsiders, specifically his customers? However, running a startup for a year now, I find the act of writing a business-plan always comes second after doing what needs to be done to keep the business alive. Still, writing offers some reprieve from the day-to-day stress and I'm much better versed than my co-workers on the grander vision and how to get there.
Will a business-plan get you funded? It did in our case, from a governmental institution, but all the real investors I met preferred two things: a working product ready to launch and a clear financial overview of the potential return on their investment.
From my understanding, you can file a patent and it will be in application for 1-2 years (at least that is the period here in EU). During that time, it doesn't have be publicised (one possible reason why you couldn't find it), but if someone else were to do the same thing, it can serve as a tool to claim prior art.
However… going to an actual patent raises the costs substantially, more so if you want to be protected in multiple countries—translation-costs, etc. and the total cost can easily exceed 50,000 dollars. Also, as someone pointed out, having a patent doesn't cover the cost of suing someone infringing on it.
All this taken into account, I doubt that very much can happen to you if you infringe on it, unless this is truly a million-dollar product, in which case protecting a patent pays of.
Worth talking to a patent-lawyer in any case though, for reasons on how to circumvent a future patent.