My partner is skeptical of using key cards (which I think would be the easiest/best route) as he thinks they have too much potential to be demagnetized and cause us a lot of work. 

We have a half done rehab in north lawndale and already seeing new highs for the 2 unit comps, it seems the fastest growth is 2 units in areas that become more popular for owner occupants huge equity to be made. 3/4s cashflow more and more but not seen the % appreciation of 2s and houses. 

Hello and thank you very much - the tenant has a free standing heavy bag on the front porch of a half duplex and the floor is wood. 

I agree that it would probably be the easiest to buy an existing duplex or house that has ability to be split or easily added onto.

For them, that was the easiest and quickest fix.Not many people will sell subject to the mortgage, but a few will.

The easiest way would be to look up the permit history for the new construction. 

126 numbers is less than half a day's work for a cold caller with a system.

It would potentially yield 50 potential closures if one really worked up all those leads (assuming you could skip trace half of the prop owners on the list  and call/email/mail them). 

There are tools that can be used to help determine ARV, but perhaps the easiest is to obtain a value from a realtor.  

As others have suggested, C4K is easiest.