Another thing you could do is to prepare a scope of work for each unit and acquire bids, ideally 3 on each item. 

I factored in the two biggest CapX items (new roofs, new boilers) at purchase to arrive at my offer price...  

Will depend on several factors like the type of property, type of tenants, your risk tolerance, other assets you own, your estate planning, laws where the property is located, etc.Any lawsuits would be limited to the assets of the LLC and not your personal assets (assuming you run the LLC appropriately and the corporate veil is not pierced).

I would love to be near the Glen Ridge, Bloomfield or Watsessing train stations ideally since my wife needs to commute to the city.

Depending on the strength of the market, I will charge 15 - 25% more for a month-to-month lease to mitigate the increased risk of departure under less-than-ideal circumstances.

What are the fees, penalties, or other main factors to consider with these accounts?  

Questions I have is if it makes sense from an ROI standpoint, as my several pro forma calculators don't really factor in these 'family' variables with what my Dad is proposing:Here's the scenario: Purchase duplex of $350k - $400k.

@Minnae Chabwera Ideally you should reviewing the local laws about terminating the tenancy. 

@Brandon Miller- He does both communities and single homes, with his ideal being a community.

However, when you factor in the time value of money, and the minor(Or major) remodel needed after a tenant moves out, you might as well just keep flipping.