The key there being "reversionary interest," which would indicate that the home buyer owns the land conditionally.Now I'm not a lawyer.

This will be my first investment property.Seller does not want to use agents.So my question is what conditions should be in the contract as far as due diligence?

the best way to do this is to have lawyer write it up. the second best way is to purchase on online (BP sells state specific leases, prepared by attorneys) and you can always make some modifications to it...but the most important part is to run the purchased lease by a local real estate attorney to make sure it and any additions comply with state law

(a) “Common Area Operating Expenses” are defined, for purposes of this Lease, as all costs incurred by Lessor relating to the ownership and operation of the Project, including, but not limited to, the following:(i) The operation, repair and maintenance, in neat, clean, good order and condition of the following:(aa) The Common Areas and Common Area improvements, including parking areas, loading and unloading areas, trash areas, roadways, parkways, walkways, driveways, landscaped areas, bumpers, irrigation systems, Common Area lighting facilities, fences and gates, elevators, roofs, and roof drainage systems.

I've got a call in to my lawyer to draw up the sale contract. 

I’m not a lawyer so I will not discuss details of less other than it probably transfers. 

Please read those fine prints and consult with lawyers. 

I have seen several homes damaged due to mold and/or warpage of doors because the owners didn't want to pay air conditioning bills.

Conversely, applying a reflective layer below the roof truss space will help keep the conditioned space of the building cooler in the summer, but may have little (or even an adverse) impact on the temperature of the roof deck itself.

Real Estate agents are not needed to buy and sell property, there is no laws requiring the use of an agent (To answer you example in italics, yes I would contact the defendants lawyer to get information if my lawyer wasn't doing their job also, also because of disclosure of information in a legal case I wouldn't need to contact the other lawyer.)