I read couple of books about REI, and I understand that during first years of investing I may do more mistakes and I want to make them frugal. 

If you are frugal, read Rich Dad Poor dad, you can put some good money in your pocket.Good Luck.

They now require 24 hr care and he is trying to avoid selling his home to pay the $65k that is owed.

Read as many RE books as you can get your hands on.

"....I read a book once that told me to do this...." words to live by, and also words to die by.  

Andre - For starters I would recommend you read "Short Term Rental, Long Term Wealth" by Avery Carl;   You can find that book right here on BiggerPockets. 

There are a ton of reviews of Propstream and other systems people use here on BP that you can do a simple search to read the reviews

I understand that notes is a business best learned by doing, but I am trying to lay a good foundation of knowledge as a starting point.To date, I have read these books:"Invest like a Bank" by Beaux Blast" Little Green Book of Note Investing" by Fred Moskowitz"Real Estate Note Investing" by Dave Van Horn"Note Investing Made Easier" by Martin Saenz"Invest in Debt" by Jimmy Napier"Profiting from Non-performing Mortgage Notes" by Amed HazelI welcome any thoughts or recommendations that the group may have.   

It is the agent's responsibility to make sure all parts of the selling process are taken care of properly.

Buying based off the things you read on this forum would be purely speculative.