When someone else buys the building and wants to live in the building they can only inhabit that particular unit. 

I also want to be able to rent or inhabit either one if it is not sold within a few months, as I cannot sustain a vacancy in either for more than 2-3 months.

Do houses that are rented/inhabited sell easily?

You may not have been aware, but all you had to do to was negotiate a reasonably quick timeline with the PHA to make repairs/renovations to fix/replace the HVAC and assure them you would be meeting the letter of the law in proving other accommodations for the tenants during any time where the unit would not be inhabitable due to the work being performed.

Shaun:Once upon a time it was fairly common for side-by-side units to be built with a double wall, each faced on the inhabited side only with the cavities either empty or filled with paper-backed insulation (fibreglass, mineral wool or gypsum wool).  

Many people try to shoot from the hip on that, but there is nothing like the cold hard facts to inspire change in habits.

I my self had some pretty rough goes with it in Detroit I walked away from 2 homes that I let go to tax's and lost right at 100k... its a rough rough town and really not sure if its fixable or many of the low life inhabitants are fixable.. there was a pretty compelling pod cast about the whoa's of Detroit a few weeks back.. obviously there are good ares of the city but the bad one's boy are they bad.

By law, the landlord must make sure the property is in "habitable" condition.

It is currently not inhabitable.

Yes they are cheaper to install but part of the reason for that is that all the other hidden costs which come with them, such as shorter life span, proper disposal, toxicity to the environment and household inhabitants, are all costs that are shifted to other parties who must pay the bill down the road.Vinyl is lethalWhy we don't install vinyl windows