I rented the house, what would you suggest I do with the empty lot to maximize profit? 

North Minneapolis can be very profitable.

It is a good thing that you are still employed, I think.If your are stressing the importance of long term investing  I would probably recommend the same thing because of the current economy would mostly make a Fix and Flip or a Quick Flip scenario and not get a loan to do any repairs if you feel like you would still make a profit. 

This begs the question of whether it's more profitable to do long term rental leases or short term vacation rentals or even an Airbnb setup for these properties.The main reasoning here of course is the still very depressed prices offering high potential for return.

It would be a money pit for me, and I would have to hope for appreciation to make it profitable.

you can do one of several things. you can include electric in the rent (not always a good option) , you can stipulate, in the lease, that the electric bill is split 50-50, you can implement RUBS which divides the bill into the percentage of space it takes up (for example one side is bigger so they pay 60% of the electric, or the 2 bedroom pays 66% and the 1 bedroom pays 33%), or you can submeter the electric which allows you to split the bill you receive according to the actual electric used, finally you can discuss with your electric company what needs to be done to add a separate meter to the duplex. submeter and second meter are most expensive options, but in my opinion are the best for your long term sanity and profit.

@Dennis M. a lot of different non-profits.

@Micki Sluyter, The IRS has a funny (not so much) way of accounting for profit when you do a 1031 exchange.   

I've also have done a little learning about SD Accounts too.I think all of what you said is true but you may have to buy it in your own name them transfer to the SD-IRA account name but you must understand that any profit stays in the tax-deferred account to be income tax free and not penalized.   

Ok seasoned spec builders,What is your most cost effective/profitable home plan?