Again the rent would only cover a portion of PITI.

I don't have any idea if they (son/wife) will be actually paying any portion of the rent.

What portion of it you receive is dictated by your independent contractor agreement with the broker.  50/50 is typical for a low volume agent at a big name brokerage, and then there are places that give you back much higher.

Give a copy to the tenants when getting them to pay their portion. 

It will become my primary residence while collecting rent from the business portion, so I’m not too concerned about the cap rate while I live there.

Originally the seller wanted to finance more with us, but due to his own tax situation he just did the down payment portion.

This quote was to remove and replace approximately a 15' x 15' portion of that area. 

@Gregory DeRossoI am a developer in northern jersey and I can’t begin to tell you how vital is it to have my license.

Fair market rent for my portion of the house is around $2,950/mo.I did part with $109k down payment (including closing costs), but I've been saving for quite some time so I still have some fairly healthy cash reserves, and I'm actually looking get another property within the next 6-12 months (most likely out of my expensive market though). 

Or will New York immediately, or sometime in the future, want their portion of tax on the gain?