Can we use just a generic letter of intent to purchase the property and also provide earnest money to seal the deal? 

The whole industry needs to make it more normal to have buyers fully approved, stamped, sealed, some special designation to show they've been raked through the coals and cleared, what pre-approval used to stand for, then somehow weed out the ones who just write a pre-approval letter without doing the actual approval process just to get business. 

You need 2 Navy Seals to be living on site to be successful there.

Seal off any room that is not getting sanded with a plastic 'curtain'.

Right now, though, we are working on acquiring, analyzing, offering and sealing the deals.

If so, I would discuss with neighbor about letting you (read: sweat equity) power wash it and stain/seal it.  

To make the cabs last I glue and screw everything together and silicone seal the perimeter bottom of cabinets in case a tenant spills water it won't get into the seams.

Just notify the tenant you need to do some preventive maintenance of the property, such as checking the condition of the HVAC, window seals, electrical outlets, etc. 

Philly requires the newer 10-year sealed battery models.  

Thanks to Biggerpockets I have sealed a deal "Affidavit and memorandum of purchase and sale agreement" and this deal is not listed on mls!