Significant in absolute numbers when the country has 122 million households. 

In markets where the median home price / median household income is very high, a higher interest rates will have much more of impact in housing prices compared to where the ratio is very low (lower than 3), thus the housing in the area will be less impacted.

I am looking for suggestions on comprehensive information / course material, forms, etc on the business of “Hard Money Lending”.

I've advertised many household items on craigslist and most have sold within the first day of posting.

Coney Island and Brownsville neighborhoods have median household incomes of $9500 in 2013.

Remember that an electrician does make good money after his apprentanceship but it is seasonal work so your household income may fluctuate throughout the year.

The overall vacancy rate is not atrocious, 11% which tells you they rent fast for right price.You are in a low income area, median household is barely $36k/yr. 98% of the local residents didn't go to College, so you get an idea of the wages. 

My wife and I are fortunate enough to earn enough from our 9-5's to make well above the local median household income, but are not in a position to start purchasing property for cash.

Banks will be looking at your DTI as a household, so those debts of your wife's may be part of the issue- you don't mention if that's a very large number, but those car payments can really add up.You are in a good position in terms of having plenty of equity, but as I have learned from personal experience, equity and $4 will get you a cup of coffee at Starbucks, lol.

We have talked about doing this for 15 years as we have rehabbed our own houses and believe this would be a good time to strike.Our ultimate goal is to obtain 10 rental properties in the next 5 years to create enough passive income to run our household.