So at the time they were built, if they had specific stairway width etc.. they should be all set since they were made before new regulations were introduced 

Saying roof needs replaced and septic/plumbing lines are bad and are trying to back out of lease.

There are a couple properties I have my eye on that are going up for sale soon....I'm having a title company do title searches on each one to determine lien position...both properties are vacant, so the redemption period is only 30-days, but it's unclear to me if it is the foreclosing bank or myself as the sheriff's deed holder is the ("mortgagee") who determines if the property is "abandoned in accordance with MCLA 600.3241a"Based an exterior inspection, the bank has already seized each property by installing padlocks on the doors and winterizing the plumbing.

If you just do the SFR, then there isn't much that needs to be done in terms of code enforcement (depending on the level of rehab, they may specify new wiring and plumbing).

Either way I just got the inspection which revealed a plumbing issue that I wasn't aware of.

Did they just do new cabinets and carpet or replace electrical,plumbing,etc.?

I have renovated all apartments within last ten years so keep in mind I have all new electric, boilers, plumbing, bathrooms, kitchens.

Before you proceed take the time to study your state landlord tenant regulation.

Cons: 1. 4+ family in NJ is subject to state regulation/inspection/tenant protections.

Your local zoning officer would be the first place to start, then there should be some state board that regulates hotels, they would have some input.FWIW: really bad idea.