However, I assume you intend to self manage your rentals.

Its called the self sufficiency rule.- you cannot use non occupant coborrower for income purposes or you may have to increase your down payment significantlyAs for other underwriting guidelines, its pretty much the same as any other FHA loan.If all units are occupied you'll need atleast one of the tenants to write a letter to state they intend to move out by the date of closing.

A home without an operable/sufficient heat source in the winter is considered uninhabitable. 

To quote Lil Wayne: "Real G's move in silence like lasagna" ("G" as short for a gangster, hustler, a self-made successful person)It's a funny play on words, but like a lot of rap lyrics, it's actionable advice.

One contract with all owners is sufficient and I think the only way to do it.

Sounds like you might want to look at moving some of your IRA money into a self directed IRA.Hope to see you at the next Meetup.

I am a self manager and do all maintenance. 

If the cashflow and cahs on cash return is sufficient when including the HOA fees then I invest.   

Now to be completely self serving :), my firm is based out of Los Angeles and we can provide references.  

So I am self employed as a consultant in a business other than real estate (I also have some rental properties that I own and operate but I don't believe they are relevant to this question).