I clean, wipe and vacuum obsessively almost every Sunday.It is only with these guys that I got "extra charges" for some "unknown cleaning costs."

If you plan to use the HELOC for your down payment until some unknown time in the future then I would pull money out of your primary via a refinance with a fixed rate. 

Somebody wanting to sue for you backing out of a bad deal or accusing you of selling them a property with defects like unknown termite damage).

If you have a good deal come your way but are hesitant to pull the trigger, referring that lead to someone in your network/marketplace will go a long way in building your reputation in the marketplace.Be sure you have solid reserves for the unknown.

I just wouldn't want some unknown risk to sneak up on me so I'm hoping investors with experience in piggybacks or portfolio loans have some counsel they can share...

@Kellon Parkinson everything seems like it’s going to be a mess and a lot of unknowns for a period of time.

Our next step at this point is unknown for us, as new construction drains your capital very quickly.

That's a lot of unknowns and risk for a 4.8% CoC return.

Business partners are exempt lender/borrowers or where you have a small enterprise (usually 3 or fewer parties) with a common business goal.This can be tricky for a lender when they create an obligation to a business entity or Trust, as all natural persons involved should be known, however a private lender may lend to one other party who is unknown to them when the know party introduces that unknown party and those parties have a relationship. 

An awful lot of unknowns in your question . . . you are saying it has an ARV of $275/ft2 but what is that based on?