Would it be easier to write a specific contract for each sum he transfers to me and have 5 or 6 individual notes with descriptive verbage on the terms?

I am committed to testing the short term model this week through the summer, as I've just dropped about $5k on supplies/set up for it, hahahaha (all a write off)  I'm just testing the short erm/ corporate rental/ vacation rental model on a few units. out of about 30 that I manage in this area.I'm setting up beds, furniture etc this week and hopefully will have some rentals open this week.I'm attempting to do corporate (mid term 1-12 month furnished rentals) as well as testing the Air BnB concept.If any locals who do Air BNB on asmall or large scale want to help for service, Or if a local newbie wants to meet up and help me move furniture, clean and set up these units let me know. 

I’m now going from driving, writing down addresses and observing, to writing letters, visiting divorce courts (Weird, but it’s a strategy), and several other methods I’ve picked up to find some great deals.

By renting to them at ~$10k below market annually, you are essentially writing them a check for $10k each year. 

I doubt you’ll have 700k to just write a check.Nothing you say will chAnge my mind that seller financing here is a good idea.  

Write up the contract and have seller sign ( standard 1-4 family, TREC form in Tx)2.

As someone said - first thing to do is get her affairs in order if you haven't already and have DPOA's set up for finance and health if 2 people will be involved or just one for all affairs - definitely consult an attorney and get everything in writing - if your family goes and invests her money and you lose it or there are not checks/balances and someone is essentially embezzling money you're asking for trouble and can cause her all sorts of issues.  

He is willing to pull some cash out of this house to assist with some of the repairs also (so he has a mortgage to write off or tax reasons).

Or do you just have your real estate agent write up the contract with you specific clauses? 

the NMLS test is VERY hard to pass unless you have been writing owner occ mortgages for years and fully understand all the alphabet agencies out there..