So once we let a tenant know they’ve been chosen we give them 48 hours to put down the deposit which holds the unit until they sign the lease.

Investors Wanted To Believe though.....I saw people pay $50k Over the HOA judgments on that gamble......a nice surprise for the homeowner who hadn’t paid his mtg for 6 years......not so good for the buyers.

Otherwise you will be gambling. 

For me anyone with a fico below 560 is probably a life long deadbeat, and anyone with no credit file, probably is also a dead beat, but they could have no credit for many reasons other than their lack of credit worthiness, so I assign 25 gamble points to the no credit renter and treat them as equivalent to a 585 fico.

The fourplex is 1,015 for 1st and 2nd floor and there’s land all in front big enough for a parking garage or another fourplex if chosen to do so... the MLS is even throwing me off.

Liquor and porn always was chosen first.

That said, in many circumstances it might help. it's a gamble at best imoI also assume this is for a retail primary home, if it's for an investment house then I really hate this idea.

Also, if my goal is to purchase a multifamily home - live in one side and rent the other side - do they (and if they do, how will they) include the potential rental income into the mortgage if I don't have a property yet chosen?

The numbers in the tool are as reliable as the data chosen to perform the analysis, and that is up to you, not the software.The tool currently uses Zillow data to suggest a number of comps for you, however you still have do the work of verifying their suitability for your analysis.

So for this method, I have chosen the route of rental properties.