My wife is leaving her teaching job to join me full time in real estate and because we will be a fully self-employed household we are worried that a conventional loan is going to be out of reach (Hillary is legally employed until end of August).We have about 10% that we can put down on the purchase of the house.

So far, all my questions have been answered through a bit of searching, this is a very comprehensive collection of information.  

But basically, if you are looking at multi-family housing anywhere, two key metrics to look at include average household income, and rental prices.If we figure that once a wage becomes unlivable, then rental prices have to drop.

They are not as stable as a higher income earning household that may be looking for a rental payment between $1,000 and $1,500.  

RE investors are BIG on sharing info via books and other means, but the books are the most comprehensive source I've found.

Cottage Grove is perceived as moderate in household incomes but that isn't actually accurate.  

We had a family of 5 but had as many as 8 in our house hold.

This answer isn't helpful, but you're looking for more info that can be comprehensively given in a post. 

However Baltimore is the only city in the top 25 markets where the rental rate of return is over 20%Baltimore has one of the most stable economies in the United States, median household income averages $70,000 which ranks #4 in the U.S.Baltimore’s millenial population has grown 16% in the last 5 yearsBaltimore has over 1,000 miles of natural shoreline making it one of the most beautiful places to liveBaltimore gets over 2,000 hours of sunshine a year, rivalling Florida as the “sunshine state”Over 2.7 million people reside in the region making it the 20th largest metro in the countryHigh opportunity and relatively low home prices make Baltimore one of the hottest Real Estate markets in the nationProperties can be purchased in the $70 - $85K range and rents range from $1300 - $1600 a month for 3 - 4 bedroom homes.

However, in general the population has a median household income of $45k.