I don’t have any other hesitation other than the total income they receive from their jobs not being sufficient (at least 2.5x the monthly rent), but should I consider the six months advance rental payments knowing they will have access to additional income made from the sell of their home?

They can allow you to access markets outside of your own, which can be invaluable.

There's no way I'd own more than a couple of houses without it, as the ability to leverage would be so limited that only the cream of the cream would have access to those funds.

A to Z Home Improvement.

With a little cosmetic improving it would be worth $165,000. 

The purchase price is 399k.I am working with a partner and we have access to 150k, but not 400k.

You can look for someone who specializes in selling that product but they will most likely be a Farmers or Nationwide agent that has access to quote with those carriers. 

While you are working on cleaning up you debt, you could also work on improving your knowledge in Real Estate and get familiar with all the other Real Estate investment strategies, Learn how to analyze random deals, ... etc.

I would actually be at more of 50% equity position based on improved NOI.

Can anyone recommend a low cost brokerage in Massachusetts where he can renew his license and maintain MLS access?