New mechanicals, new roofs, tile in all bathrooms/kitchens, granite counter tops, hardwood floors, huge walk-in closets, laundry rooms, open floor plans, new siding, new windows, spray foam insulation.

I wouldn't just tape those up.....Hard to tell on pix, but it may just be dust that is accumulating in areas due to normal air circulation/turbulence....if that's the case, you really just need to clean the unit up...... dust will kill the efficiency of cooling unitsWorst case is that its something liquid leaking and its blowing that material across that surface and dirt is sticking to thatBy sealing it up without knowing the issue, you are just encasing the issue out of site and will likely just postpone needing to deal with it.Id take the covers off and take  a better look....my gut is that's it dust material

Should the Purchaser default for any reason, Broker shall retain all payments made as liquidated damages up to the amount of commission."

Lenders have declared they will NOT lend to TICs, so that is going to become less popular, not to mention less liquid. 

They are going to ask for a plan and bpo's, contract (if available), liquidity or cash you are bringing to the deal, anything you might haave to put up for collateral and a few other things depending on the lender.

I am currently working on getting an unsecured line of credit for my company while also building as much capital/liquid assets as possible.

The owner wants a cash buy, the less contingencies the better, and to liquidate fast so she can purchase property out of state.

Perhaps I am being too paranoid, I worry about a large apartment investment deal being forced to liquidate during a downturn, perhaps this doesn't happen often. 

Stocks are also very liquid.  

We would split all cash flow and liquidation proceeds (if we decide to sell in the future).