BUT the seller has been doing some major renovation work (new bathrooms, plumbing, electrical) but without Chicago permits. 

I had to put in new electrical and plumbing, which was costly.

Is the landlord paying electric?

Don't forget the electric, water, sewer, gas bills you will be paying during the rehab process.

I was told they only look at hvac, water and, electric.

I also do not believe the electrical is up to code because my contactor friend told me there are supposed to be electrical outlets every 4 feet I believe.

We own another duplex in the area that has done very well but bought it 7 years ago.Sale Price: 426KBeds/Baths: 4 beds 2 bath on one side/ 3 beds & 1 bath on other side which can be upgraded to 4b/2bath.Closing costs: $8749 on Mortgage:  4.5 % 30 year mortgage with 25% downRepairs & Rehab costs: 30-50K to add AC units, new furnace, new electrical panels both sides.  

There is only one electric and gas for all the tenants.

No, because they have cable to pay, they have electric to pay, food to eat, going out to do, purses to buy.

I do plumbing, electrical, basic framing etc. the only things I would contract out were siding, roof, windows, HVAC.