You would need to have it notarized by someone recognized in the US system (you can usually get this done at a consulate).Defiantly consult with an attorney so she can't come back latter and claim she still has a half interest in the property.

Bandit sign, legal or not, are just another type of graffiti in my humble opinion.I wish you well in your business.

And the deals in FSBO and foreclosure and probate and what not are deals more geared towards the wholesaler or bird dog and investment buyer.  

You say "Dodd-Frank was designed to protect individual borrowers - homeowners - from predatory lending practices"....well if I seller finance a home to someone, regardless of whether they occupy it or not, are they that an individual borrower and a homeowner?

., it is actually in the tenant's lease that "all repairs, whether to be done OR not are at the discretion of the landlord". 

Also, does this contract need to be notarized by a lawyer so that the investor doesn't go behind my back and purchase the property?

I have the buyer sign them and get them notarized.

I plan to type up a document with the court house record info and state my purchase of 50% interest in the property and have it notarized.

Does the warranty deed need to be notarized in-home at the first meeting, or can I instruct the buyer to have it notarized at their bank and mail it to me (to document their willingness to sell)?

If not are you expecting any such suit to be settled for less than the value of the policy?