Also you never know what the municipality can/will do to make you life a PITA if they catch wind that you are using a place illegally as a 2 family.

In addition, think of the illegal money that could be easily funneled through these.

I think the government spends too much time telling us what we can and cannot do.If the referral fee is illegal, what would keep the agent from hiring you to go put up their sign for $500?

If you have control over these things, you have an employee, not a contractor, and you'll be on the hook for employer taxes/withholding and potentially workers comp insurance requirements...among other things...

The liability I can get it for $600.00 (year) or I can see if my current home policy will extend to the new property. what kind of coverage can I get for when I hire independent workers that are not cover under any contractor or sub contractor policies?

Then someone has to pull the file for you. 30 days equates to about 200 files, so it's very time consuming and the court house workers will hate you.In addition, it takes the court houses in MA several weeks to scan all docs before they release the file to the public.

But most types of discrimination are not illegal.

I've never seen or dealt with any paranormal activities, but I'm a believer because I've heard stories from friends and co-workers. 

One uncle has made a killing offering a boarding house to temp workers at Jeffery power plant nearby though.

If your lease prohibits illegal activity, then if the tenant gets arrested or you can prove it's doing something illegal, then you can evict him (or just tell him to leave).