I'd be looking at it from an investor's perspective.

If you look at 8 houses, and you are reviewing all at the end of the day, you can tell where one ends and the next begins,  We also make sure not to take too many pictures. 8 max of only the high ticket items, roof, windows, kitchen, electric panel, kitchen, baths, furnace, ac, front and back, andything unusual,  i dont want a picture with a hole in drywall that will cost 25.00 to fix, no pictures of carpet of paint, or things we will replace in every house.... always a couple photos for perspective. 

I was just going with the assumption that you were only going to pay cash, due to your wife's perspective on it.

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I am not an attorney and this should not be taken as legal advice but as a guide to better understand your options coming from a small business owner perspective. 

It puts it into perspective when I get to that level someday :)To clarify, I would like more passive income VS short term income sources, aka flips or smaller short holds. 

A real estate license also will not hurt, it gives you perspective to the buying/selling portion, broker guidance, and most importantly MLS access [your dad might have access as an assessor].Sidenote: Keep your grand plan of owning a Ferrari a secret, for now.

This method is really great fun as you can always discount the note in the future, or renegotiate if the market shifts. 

I know that prices shift, that they generally go up when the notes are secured against house with enough equity to cover the UPB or if the 1st is current when buying a 2nd, etc - but as a rule of thumb, what is a reasonable offer and what is crazy talk?   

From an owner's perspective, tuckpointing, roof and sewer lines matter.