I was considering getting my brokers license ( MI requirement is 3 yrs in RE and Builders Lic. counts towards that) but not sure if it can negatively affect my investment business.

While I certainly don't count on it, I project these houses with double to triple in the next 10 years.

I would recommend to learn the fundamentals so you know the "why" of a good deal and be able to eval each one without this, but its a great shortcut.Definitely make sure to check out the podcast...53 episodes and counting...it's a wealth of information.Best of luck Greg!

She will certainly do this to you as well on the back end of her lease, you can pretty much count on that.

I check out property tax records and cross reference other homes they own.

There's a chance that you might cross path with them in the future. 

Use zillow to get the comps you need to come up with your own estimate.To me, I have a pretty simplistic approach to estimating.In Zillow, I enter the address of my home and click submit.I then modify the default filters based on my subject property's key characteristics: Bedroom count, square footage and age of home. 

Not even counting dealing with the rental or maintenance costs. 

They insured the house and counted the back units as an outbuilding.  

They also know when not to cross the line, and therefore keep you out of trouble.