We'd like to tap into this equity but discovered that borrowing money when an LLC is involved produces rates that are so high it's difficult (borderline impossible) to cashflow from properties in the area.We'd like to consider taking personal loans or HELOC as the rates are much more appealing and it allows us to still tap some of our personal equity.

So, although I understand that a HELOC and/or Mortgage is considered equity stripping as your are literally pulling the equity out, as well as the "safety" of having an insurance policy, and the dilution tactic of ownership parsing throughout multiple entities. 

I think a HELOC is out of the question due to credit score, same for a lump sum reverse mortgage.. is this something a Hard Money lender would consider?

I would recommend a HELOC, Pen Fed Credit Union offers them on investment properties.

I am Having trouble calculating ROI. If I am financing with 20% Down payment do I calculate my "all in cost" of the property as the 20% or the actual purchase price of the home? Thanks in advance!

With a cash out refi you will play closing costs, however, you will pull out the equity and not have anything to pay back (unlike a HELOC). 

Source of down payment funds, if applicable: Could do HELOC (maybe) but only have 22.4% equity right now. 

Or a line of credit (HELOC) on the duplex? 

So I was thinking since I already have 30k in business credit, received 15k in business LOC today and bank will front me 30k HELOC on the 40k rental I own which brings me to a total of 75k, which means I need 25k more.

They both offer HELOCs on investment properties.