Stocks/Index funds are my comfort zone, yet I've never considered pulling equity to buy more stock, or getting a loan (unless I'm playing RDPD Cash Flow game, then it's risk taking everywhere....but that's my virtual life/family in that game, so who cares if we go bankrupt?). 

You do not install anything extra in a rental that you will ultimately be responsible for maintaining.

I haven't looked into these much before but they seem extremely renter friendly and cheap to purchase/maintain.

My opinion is based on maintaining respect for all landlords, HOA or otherwise.

When a stock market crashes, it loses 10+% in a day.  

People need to maintain and operate the machines and there are tasks robotics cannot perform. 

Insist on work and payment request verification independent of your partners - i.e. don't let the guys spending the money maintain strict control over who it was going to and for what it paid for, even if you have to be the independent verification service yourself. 

Also I would want her to sign an acknowledgment letter stating that her fence is not against my will and that she must maintain the fence and land.Also while I have your attention, what should I do if she refuses?

I would use this to educate myself on purchasing properties, managing properties, maintaining properties, rehabbing properties. 

@Jay Hinrichs your message hits home with people like me who have seen several cycles (Real Estate and stock market) since the 1980s.