Light electrical, light plumbing, light light construction.

Painting is another good thing you can do to save a few dollars.As for what you should do, always kitchen and bathroom updates (lighting, hardware, counters, cabinets/vanities, plumbing fixtures, faucets) should be your top priority.

You could pay for a home inspector, termite inspector, plumbing inspection and roof inspection and then decide you no longer want to purchase the home and you will be out all the money spent on inspections.

Probably electrical and plumbing as well as a kitchen cabinets.

Make a master bedroom by closing off some existing walls, and run all new plumbing for the masters connecting full bath and build that bathroom up as new...

Family owned and operated, we have been doing plumbing & heating since 1978, including kitchen and bathroom remodeling.

The mortgage on the 2-flat we could easily pay with our 9-5 jobs so vacancy wasn't really an issue - we could absorb it if we had to and did for about 6-months while we had some major updates performed on the house (new HVAC, 2 bathrooms gutted, new plumbing in one unit, etc.).  

Plumbing.

Add sub panel if needed (which is probable given the number of home runs needed when remodeling kitchens and baths now)plumbing: cut out and replace any galvanized drain lines that are accessible at any point in the project.

I would like to try to put together an option to purchase the property as is, of course after doing all the proper due diligence. ( I suspect that much of the electrical and plumbing is shot...lots of work to bring it up, but it could be a beautiful place) Can anyone point me to a basic investor formula to evaluate a reasonable offer for this type of property as is, and determine what the percentage and length of an option should be?