When you have a duplex and tenants on both sides stay for ten years, it almost guarantees that something isn't right.I would study your market and determine the value of your rental, because I bet you are losing money every month.

Most institutions have a 70% limit. 

Study the market.

Lost time-  you don’t find this out till your Geometra does his study.     2.  

WHAT IS A COST SEGREGATION STUDY?

Is there a limited number of licenses? 

First step for you is to study investing in income properties.Generally a rental property will have in the range of 4% -50% of rental income going toward expenses to maintain the investment before debt repayment (mortgage). 

I have been studying for my real estate exam, and am excited to pass it in February.

This limits your refi options when you take your scores down under 660. 

That limits LTR possibilities IMHO to some degree.