If she was actually residing in FL longer than PA for each of the last 6 years she's actually been breaking the law in Pennsylvania by still claiming to be a resident there (why would she do this, since FL tax and homeowner protection laws are better in FL?).

The reality is ADUs, casitas, mother-in-law suites, etc have existed for decades, much longer than the fairly recent state level ADU laws some of which are already 5 years old.  

The states we invest in are landlord friendly states because we only go to areas where the law favors us.  

As a buyer and you use a hard money loan to purchase and rehab a home the lender should issue a 1098 just as any other mortgage lender holding claim to the title correct?  

Keep in mind that you'll have unique issues with it that WILL have to be addressed at some point if they haven't already...

Know of a good real estate friendly law firm that can help with advising how to set up an investing company?

I know it may be ideal to focus on Central California since I'm about a 2.5 hour drive from there, but the landlord friendly laws of other states entice me and I get concerned if I buy in California I'll end up getting a bad tenant without the ability to easily get them to leave. 

This entails financing and various local laws and whatnot all converging for universal agreement, so herding cat's. 

The process was straightforward, and I didn't run into any issues.

From what I have seen in Colorado Springs, the lease only tends to range from half a month's rent to a full month's.Keep in mind, Colorado is coming out of a very anti landlord legislative session and you will have to stay in compliance with the changing laws.