I sued her for the remainder of the lease till re-rented & utility bills while empty which was up to the limit of our small claims court of $3300 & won a judgment.  

The M-1 rail will provide a great boost to some areas and if you're willing to do a complete rehab, it might pay off.  

I left a note but was hoping to find out where they are now since the house looks completely abandoned (boarded up windows) and there is no mailbox.

However as long as you're clear on the specifics on how to complete a 1031, I think this will just come down to patience and luck on getting your offer in first. 

I have had that happen a time or two, someone moves out early October and it stays empty until February and the only people who apply are people who just got evicted (but of course will claim on application that they have no evictions.... 

I'm curious as to how most seasoned investors who have completed these type of deals would approach the seller.

To further explain it looks like the first duplex is move-in ready and the "bonus" one needs a complete rehab and is uninhabitable.

You'll need to complete at least one, if not two deals a year just to cover those costs.

Has anyone ever successfully completed a project where you need retroactive permits?  

If you're living in one of the units, then it doesn't have to completely cash flow.