So the devil is in the detail.I had a lawyer tell me once that if you have a mortgage in your name but you wish it was in an LLC to protect from say something bad happening on your property to go ahead and fill out the quit claim deed have it notarized and just keep it in a safe place do not file it with the county. 

I'm writing this as I sit at my bank notarizing what I just described for a couple of properties.

Sure, ask Mom to have Daughter send you an email or bring you a paper with Daughter's signature on it, but I don't think you need it notarized in triplicate or anything unless you have some indication that Mom is not legit. 

Were the owners signatures notarized?  

If not, are they still within the time frame to be considered guests?

I've found templates for estoppel letters, and I'm wondering if these really need to be notarized by the tenants?

You may be want to keep one notarized in case later on you would need to prove it to a court.Also, in some state you may have to report to your property appraiser when the ultimate beneficial ownership of the property changes more than 50% so they could bump up the assessed value.

So my real question is, 1: is there a demographic of LANDLORD types that will pay all cash to fund the deal, and 2: if not, are there options out there to fund the deal without full cash from the assignee?

get in in writing, notarized, written by an attorney, etc.  

Happens every day.....Fedex and your signature has be notarized.....typically at the American consulate when out of the country, but your JAG office may can help.