I'm breaking this up to avoid a gigantic wall of text.
Assuming you don't have the $200,000 (conservative estimate) to pay people to engage in a project like this you're obviously going to have to go down the freebie and charity route.
Also assuming that you've put together a good design document, pitch, business case and legal setup (the open source community covers a lot of these bases thankfully) consider this.. or look at this. Sourceforge.net currently has 21,965 projects in the "Games" category. Of these 3096 are listed as "Production/Stable" i.e. fit for release, use and making money. Twice that number are listed as "Planning" and 677 are listed as inactive. My point is, not many projects make it to completion.
This is a major pitfall - people don't want to work on projects that never see the light of day, it is discouraging, disheartening and almost ensures they won't want to work with the people they see as being to blame for the failure of the project to reach completion. So ask yourself if you are willing to see the project out through thick and thin because if you aren't you're doing yourself a disservice and an even greater disservice to the people you hoodwinked into spending their time and energy on the project. The game development community, even the indie one is SMALL in the greater scheme of things and your name and reputation is very important. Failures are forgivable but walking away from a project or sinking it is not.
Which brings me to my next point. Everyone on these forums, or indeed ANY game development forum are here because they're interested in making games, typically their own. Everyone's time is finite and you need to persuade people to give some of that precious resource over to your project. So why should *I* take time away from my projects to develop yours? What makes your project a more enticing prospect than me realizing my own dreams? (I'm not trying to be aggressive here, these are thinking exercises because you'll need to persuade people of this mindset). The people you WANT to help on a project are the competent and skilled developers and artists and they're the ones you need to persuade but are, unfortunately, the hardest to persuade.
Finally, if I come across as condescending, patronizing or rude, that was not my intention. This represents my own experience (both as a hobbyist and a professional) in areas related to what you are talking about.
Thats my advice, take it or leave it.
Edit: I appreciate the irony of going on about spending an hour writing about how a person's free time is finite in response to what may well be a particularly crazed bot thank you very much.