So for example if you decided to convert the car wash site to McDonalds would you get a water credit since the water use would decrease significantly?

They basically occupy two bedrooms with a bath in between, one of the rooms converted into a modest kitchenette. 

For instance it is zoned to allow a duplex but I couldn't see anyway to convert it over given the structural constraints.Thanks!

I prefer to not touch them, as I think there is extra liability from renting out non conforming units and they have limited exit strategies, but if I did buy one I not only wouldn't pay extra for the non-conforming additions, but I'd also want a bigger discount such that converting to original and flipping as a single family was a profitable exit, thus restoring this as one of my exit strategy.

That's how Swany did it, if his condos in Ohio not in San Diego, he couldn't later 1031 into apartments. the difficulty is to convert dead equity to cash flow.

Should you convert the attached 1-car garage into additional living space?

During the downturn, the floreclosure wave hit Crete hard and some of its housing was converted into section 8 housing.  

When you refinance a property, it's already in service, thus no adjustment to depreciation.Special rules apply to primary residences converted to rentals.You should understand how refinancing a property will limit your ability to write off the interest.

I might add, when I was trying to sell initially (at a loss), it was not yet converted to a rental property.  

The reason why I'm still considering it is that my longer-term strategy is to convert the current water heater closet into a half bath, and THAT will result in higher rent for sure.