By the verbiage used in your post it sounded like this is what you received; however, I realize that the precise meanings of different terms can vary between parties if they do not know the formalities.

No formal stats...and nothing newer than 30 years old...the difference between 30 years and 100 years old hasn't been significant.We've done several roofs and replaced lots of air conditioners.  

Does this give her reason to stay in my home until formally evicted?

If you are unsure about the investor paying you then yes write up some type of formal agreement.

It's not 100% black and white, but here's a good article on it: https://www.law.cornell.edu/we...If I were in your shoes, I'd call the agent's managing broker and ask if they have any thoughts before you file a formal complaint with your state's real estate commission. 

I appreciate all the valuable information provided on bigger pockets and I wanted to formally introduce myself and get started meeting you incredible people.

I have a lead through someone I know of a group of retired professionals with money to lend, although they, nor myself, have any formal idea of what to do.Can you good folks share how you've set up promissory notes, or shares in an LLC, interest rates, terms, etc. on how you've set up deals like this? 

It formalizes what you told her and if she fails to comply, you can offset her security deposit for damages and evict her.

Upon the formal signing of the lease and key turnover, they will bring security deposit plus first months rent.  

To calculate that I would need a formal source that would indicate the useful life of a typical quartz countertop.