And if I want to add a bathroom, what should I calculate to plumb that?

I once saw one that was hung in a small bathroom.  

Is this a single home renovation, new construction, upgrades for kitchen or bathroom?

Its a 6 unit building with 3 beds and 1.5 bathrooms per unit. 

Purchase price: $170,500 Duplex2 bedrooms 1 bathroom per unitUnrented GarageBig back yard and deck off upper unit What made you interested in investing in this type of deal?

I suspect one of them is about adding a section (extra rooms, bathroom, extension to the basement) to the property (there is no description on the OPRA report, I plan to call the town to confirm).

But if you plan to finish it then rent it, you would just be looking at that as added square footage, an extra bedroom or two and bathroom, which should rent for more.

With this you get 30-60 days to pay for each purchase and some DEEP discounts on products.

(example holding costs could be $2,000/ month) But I could easily save that renovating 2 bathrooms on my own within a month (assuming it costs $5,000/ bathroom).

Many states here on the west coast have flat minimum wage with no discount for tipped workers.