OORE (owner occupied real estate) depending on usage is coveted but more for business owners that have a business outside of real estate unless you are a broker or insurance agency.  

Worse case scenario you have to rent somewhere short term until you start the job.I would highly recommend looking at a duplex or a single family with an accessory dwelling unit to give you more cashflow and more options down the road too.

Check out this one for the Sawzall  https://www.homedepot.com/p/ReciproTool-Nylon-Scrub-Brush-Offset-Accessory-for-use-with-Universal-Adapter-for-Reciprocating-Saws-RCT-SCB-10/204248369

Each state is going to be different on what accessory transfer fees there are. 

Knowing that they are planning to cheat the IRS makes you an accessory to the crime.

Pay attention to what Jimmy V said, because it took me about 6 months to have the property re-zoned as a SFH with an accessory unit (no separate metering) but it was all worth it as the 5 bedroom unit rents for $3,450 a month and the accessory unit (basement) pulls in $1,500 a month.

2) Sounds like there are 2 legal, conforming units and then a grand-fathered/accessory garden unit where you would live?  

Some towns allow such apartments as an accessory use.

The concept of an ADU is that it is an accessory dwelling on the Same lot as an existing home. 

Most people would rather live in a detached unit of a multifamily than an attached unit...I currently live in one of my multifamily properties that has a shared wall which is perfectly fine with me but currently looking for the next place and ideally it would be detached units for more privacy...Duplexes  generally tend to be smaller here in San Diego (2 bed/ 1 bath units are most common) and those with families and kids tend to want atleast a 3bed/2bath which maxes a single family home with an Accessory Dwelling Unit (ADU) more attractive.