We went back and forth and I insisted I was only interested in buying it and she insisted that I was going to list it and sell it for her.

She is more hooked on real estate investing than me and insisted that we move into a duplex by the end of 2018 (with our 3 month old daughter!) 

As far as I know, HML is going to insist on doing the title in LLC, which will change the options you have.

The bank will insist on 6-12 months of reserves (PITI) at closing.

Don't be misled about the earnest money deposits because if the deal bust and it's no fault of the seller, the bank WILL insist on not returning the EMD.

Simple things like:1 - getting to know the neighbors and other landlord,2 - insisting that every scrap of litter is off the ground,3 - calling owners when something looks out of sorts with their property,4 - a squeaky wheel advocate.You may have come up with your own methods, but always do something to make your investment area better beyond your property line - this will be good insurance against neighborhood decline.

Why would you insist on having a notary gum up your dealings?

I'd insist on the price being $740K or at least every penny of the $740K being accounted for on the HUD.

I always insist on cash (or a check drawn on a local bank so I can walk it in and get cash) for all move-in costs.  

The seller insists both are nothing to worry about, getting an electrician+structural engineer to take a look.