The only reason it is structured as unsecured is if 1) the borrower's net worth is substantial and it's basically a credit card or 2) collateralize funds cannot be secured for a specific reason (such as high volume inventory purchase/sales) but the ave balance stays constant.

Hello, im interested In finding off market houses for buyers in Philadelphia.

Then immediately contact all the cash buyers you just found that buy properties in that neighborhood and tell them about the house and would they be interested in buying it.

I have a duplex that is basically breaking even but we will save $550 by going from a 5.5% fixed down to 3.5% on the remaining principal (no cash out).

Well you can put me on your buyers list! 

Yes it is just a "construction" loan basically.

I know these 3rd party companies can take a hotel given to them by a buyer, reposition it, and then even manage it for you, creating a semi-absentee owner investment.  

Your realtor should at least be able to at least give you some basic information about the tenants.

That being so, what is the basic structure for buying a partial? 

You basically read a slide and click to the next.