There is no magic formula which predicts future events.

However that map also has to be taken with a grain of salt, since it is just applying a formula using median sales prices and rental prices and not looking at vacancy statistics or other economic factors associated with the area.

I should add that I am posing the question to see what others formula would be if all of a sudden you had $1m?

I believe the best policy is to adopt a conservative, winning formula, and apply it consistently. 

You've got to attempt for the MAO formula of 70%-repairs.  

Is there a genric formula you can use to come up certain fix ups on a property that I can outsource out to my virtual assistant?

@Jeff Filali you make an excellent point about the importance of ROT it should be included in the formula.

Of course, I don't need to remind you that each SELLER you intend to buy from will need to be thoroughly informed (in writing too) that your offered purchase price is likely say 30% LESS than ARV minus Rehab costs ie. roughly the same formula that Flippers use when buying from (mainly unlicensed) Wholesalers.

Is there a formula used by RE Professionals that calculates the viability of adding room additions, granny flats, garage apartments, aka Accessory Dwelling Units (ADU's), etc.to a property that meets the zoning, building codes, neighborhood i.e.

The [ rent * 75% - PITI ] formula you often see posted on BP will not apply, as that is for investment properties, and this is owner occupied (for us it is either/or, for us there is no such thing as an "owner occupied investment property").