There is nothing wrong with "passive" investors, and I'd much prefer to have them, BUT you just have to use an experienced attorney, period, if you raising any significant amount of money. All the documents have to be just so to comply with securities laws.
And really, anything over $1,000, even amongst friends, should have paperwork involved. It's not worth the money to get a lawyer unless your film is over $10,000, and usually in that case one person has put up the money, and typically they're helping to make the film so they are actively involved.
However, if that's not the case, I recommend a lawyer. In Los Angeles, most entertainment lawyers will have standard forms, they'll let you pay them for 2 hours (at $150 an hour of course) just to make up your documents for you, and then as long as you have an accountant you trust, you'll be fine.
The horror stories (I know, I've been party to one) come about when everyone is just throwing money around and trusting everyone else that's their "friend". When it comes down to the money in the end, no one is friends.
If you ever take money from a stranger, any amount, or make a deal with people, you're absolutely insane not to pay a lawyer. It's always the best money spent. Even for boilerplate documents.
We're currently trying to raise close to $1 million, so I know what you mean. The business side gets tricky, reputable legal and financial representation is imperative, but it's one of those things that no indy producer wants to spend any money on. Do it. Or end up with 1/5 of a film that you own. Ha ha. Lucky for us, our film could be combined into another idea easily. Others weren't as lucky.