I realize that once someone creates a letter of intent they can start on the due diligence phase to learn the financials, physical, and legal but what else can I learn about a property before making an offer? 

Also, for ground-mount systems, most developers require 200-300+ contiguous acres, a relatively flat parcel, no wetlands or endangered species, and three phase power line access adjacent to the property. 

SROs once populated much of NYC and has since been phased out through renovation, demolition and updates to properties.

Typically where the builder goes into a smaller town or area build a small phase and then moves out to another county or town leaving not many new builds in that area to offer new future construction home sales.

We haven't closed on the home but the home had couple of engineering problems that the builder has identified during the construction phase and have advised that they are going to provide disclosures for the same.

Only 20% occupancy at the start of the rent up phase.  

I strongly recommend a Phase 1 Environmental Site Assessment (also called a Phase I ESA).

Although we have to have positive cashflow after rent up phase of 18 months or 60% occupancy, which includes P/I.  

I don't have direct contact in the Acquisitions department as I work with their environmental due diligence team on Phase I Environmental Site Assessments.That said, I echo @Chris Martin in warning that the environmental and engineering feasibility process can easily take a year or more.  

I don't think I'll be able to make too much money off of it, but want to get an idea of what I'd be getting myself into, I'm in the research phase.