Does that mean the current state of the property when I take possession is the state against which I'll compare the move-out condition?

Is there a right of possession, is there a built in extension?

Service upon a subtenant may be made in the same manner: PROVIDED, That in cases where the tenant or unlawful occupant, shall be conducting a hotel, inn, lodging house, boarding house, or shall be renting rooms while still retaining control of the premises as a whole, that the guests, lodgers, boarders, or persons renting such rooms shall not be considered as subtenants within the meaning of this chapter, but all such persons may be served by affixing a copy of the notice to be served in two conspicuous places upon the premises unlawfully held; and such persons shall not be necessary parties defendant in an action to recover possession of said premises.

You may want to tell them to take possession in the name of an LLC and not O/O but as an investor. 

You can not encumber title after agreeing to sell, you can't have a leased property and guarantee all rights in title, the right of possession without disclosing what rights are to be conveyed. 

Working on getting a writt of possession now.

In a quiet title action he would be making the claim that he has the right to the property via the now deceased former owner's gift to him and/or via the law of Adverse Possession as suggested by @Christopher Phillips. 

Moral, even if he bought a house, he'd be the guy who didn't pay his taxes because paying the taxes just isn't as important to him as having his "possessions". 

The trend is towards mobility, career flexibility, less material possessions/minimalism, ability to travel, having less children or no children at all (i.e. less pressure to purchase a house), postponing or foregoing marriage...

For example, a seller owns in Pennslyvania, and exchanges for a property in Florida; they would owe gains tax in PA.Question 3: replacement property must be identified by day 45, and possession taken by day 180 (sale date being day 0).