Next question, if my lender says i must live as primary home, but the lender gave me 2 months before moving in, but there are corrections that need to be made based on sfh inspections (purchased home as is after the inspections - i was able to get a reduction of the overall price of the home by $5k) and it may take me more than the 2 months to correct the issues ( duct work sprayed and cleaned and new windows) do I have to move in?

Plumbing I mentioned and would be a decent part of the cost I wouldn't even worry about gas for a studio and make it all electric (electric HWT, Stove, radiant heat if you can) Duct work - I didn't think about this because mine have electric floor heaters already.

Due to space constraints, I can't put in a central unit with duct work.

I don't think you would ever recover the costs, especially if they have to install duct work, a newer furnace and the compressor.

Inside the walls, drywalled ceilings are electrical, plumbing DWV, ductwork and from maybe where you are, hot water heating.

Ductwork maybe affected. 

Regardless of how well you paint/seal, that smell is in the ductwork, wall cavities, studs, (after 30 years - ugh!)

i dont see why youd opt to use window units if you have existing ductwork. 

Currently not livable because HVAC and plumbing are not in working order. 59,900 List Price90,000 Realtor Provided ARV37,500 our cash offer (no lending because it's not liveable)40-45k - Repair estimate (roof+double layer removal, foundation and sump pump, asbestos siding removal/replacement, HVAC replacement including about 40% of ductwork, electrical panel replacement, plumbing updated from cast iron, complete kitchen and bath, chimney removal, 1100 sq ft flooring, all interior doors and hardware, single garage door, windows and 5 exterior doors, yard drainage issues and tree removal, drywall repair and other finishes, possible mold remediation)$345 Expenses (excluding mortgage) $950 Monthly Rent 

Where I am at It is 8k For all new electrical, 8-9k for central AC (assuming no existing duct work ), Not too sure about plumbing because my contractor owed me a favor so he did it free, however he did replace all of the plumbing, Flooring 2/sq ft (labor only), Got both bathrooms done for about 8k including materials, the roof should be about 10-15k Obviously its different for each market  but for a presumably smaller duplex, 90k seems like a lot.