That would probably require a professional. 

I reached out to the individual marketing the deal to schedule a property viewing, but they’re asking for proof of funds (which I expected) and a signed purchase agreement or LOI.Is this normal?

Do my 3 associates need to create a LLC to be able to do these renovations or can any individual do them, as long as proper permits are pulled? 

This would require a refinance into a loan with a 5-10 year maturity. 

(note: some sellers don't require this).

What are the density requirements?

Residences and cars are not purchased in individuals names.  

Acid washing when required is $500.

These costs for most of the individuals are considered personal in nature (unless you have a RE portfolio that is run like a business; see below).

If you ask the manager to justify a fee and he starts hemming and hawing, move on or require them to remove the fee.