Maybe this is area-specific and your location is different, but I have found that you often have to write an offer on a multi unit property first, subject to interior inspection.  

They will dig around the perimeter  of the house in the affected area and sometimes into the slab on the interior of the house.  

I would plan on the lower end of rent values when calculating your #s.I could do 1% rent to price but it'd have to be in a stellar neighborhood with all new infrastructure (roof, AC, interior, etc) to drive down expected maintenance costs over the 15 years I can finance the property for.Don't get locked in with something that's a marginal performer with no exit strategy that doesn't result in a loss.

If one goes vacant I would need to fix some plaster, do a ton of cleaning and paint the entire interior.

I am an interior designer and am going to invest in the local market here.

We also need to paint the interior and exterior of the duplex.

Interior.

It is newly painted on the exterior and interior, new carpets, hardwood floors down stairs, new bathroom fixtures, kitchen cabinets, two car garage.

It should have been part of the whole house theme prepared by the interior decorator.

Interior: we use a 3 color paint system (Base-Trim-Door)3.