My first task would be to determine the cause of the excessive moisture.

Plan on all tenants leaving and having lost rent and excessive repairs especially If rents are under market currently.Pay attention to the tenants that are there at 50% to see if the bank is "puffing".

The architect I spoke with seemed to think that its location along and proximal to a transit corridor would grant its own density bonus allowing the additional unit/units in excess of what the 5,000ish ft2 lot would allow. 

Ideally there is a shorthand or ballpark method I could use on my own at this preliminary stage to avoid excessive spending on padded research fees.

If you do not have an appetite for risk and do not have excess funds sitting in the bank/credit union, it might be in your best interest to wait on the side line and let this play out a little bit longer to appropriately assess the risk. 

When you receive a gift from a person in excess of $14,000 per year the person making the gift must file IRS form 709 which reports the gift.  

(in excess of the deposit)3.  

Please keep in mind that If you have a bad (or no) relationship with the seller, requesting excessive repairs will sometimes alienate the seller and kill your deal.

Subchapter G.If the personal holding company tax (IRC Sec 541-547) doesn't bite you the accumulated earnings tax (IRC Sec 531-537) will.The IRC strongly disincentivizes C Corporations to accumulate earnings & profits in excess of bonafide business needs. 

It's not like the major metro areas where you can go through these neighborhoods and see readily apparent indicators of high poverty/crime areas (boarded up buildings, excessive loitering, etc)This is why it's important to have someone who knows these areas on your team.