If she backs out before the predetermined date do I make her responsible for rent fee, or just keep her security deposit?

Showing him the numbers of course is the best way to secure this deal.

Per Fannie:If the mortgage loan being delivered to Fannie Mae is secured by the borrower’s principal residence, there are no limitations on the number of other properties that the borrower will have financed.

NOTE:  Their security deposit still needs to be the non-discounted rent total!

So that is how we got rolling in the early years.I do suggest that method, as we benefit from debt pay down, appreciation, inflation and the renovations that we do.  

I've calculated my number - how many units I want to get to where I feel financially secure and content with my real estate career.  

The BP community lovessss to paint a rosy picture of the BRRR method that isn't always necessarily accurate. 

Say you do the door to door method in finding deals and the seller decides to just sell to you.

What's the best method of doing this to keep from capital gains from a gifted house and such?  

I use the following method: Pull compsGet potential rent numbersGet a scope of work (costs & to-do's)Ask yourself what a realistic ARV is - or the find a few good comps you'd like to hit.Ask yourself what level of rehab it will take to reach ARV target.Figure rehab and costs based on ARV target.Add holding costs, insurance, realty fees, etc.Work backwards from target.