Per Fannie:If the mortgage loan being delivered to Fannie Mae is secured by the borrower’s principal residence, there are no limitations on the number of other properties that the borrower will have financed.

NOTE:  Their security deposit still needs to be the non-discounted rent total!

I've calculated my number - how many units I want to get to where I feel financially secure and content with my real estate career.  

And for some of the work, we would of needed a contractor since we don’t have the experience or expertise to remove weight bearing walls.

It turns out her old landlady in a similar situation had brought out a contractor and made a lot of noise about replacing the whole vinyl window, and finally charged her $70.00 for an entire new screen frame shipped from the window manufacturer.Same landlady who ate my tenant's security deposit and had never heard of giving notice before banging on the door.

I would like to secure my friend's loan with a lien on the property in 2nd position.

There's another one by a securities attorney, Gene Trowbridge, "it's a whole new business".

Also, review the closing documents to ensure that the tenants' security deposit is credited to you and that it matches what is in the lease agreement. 

At this point with only 6 months left to wait, increasing interest rates, as well as higher debt load from remodel, it may benefit over the long term mathematically with the secured lower rate, because the margins in Denver are tough.

Remote locks, security, intelligent door bells, Alexa etc.