I do not do that and don't imagine that many would; it would be way too complicated considering expense deductions etc.

. #3 gets complicated factoring insurance’s number in, and the house’s mortgage lender assuming there is one, but it should still be an option.  

It can get complicated so please exercise due diligence.

Not all lenders will do this but it is definitely a commonly used financing technique. 

Each one can come with its own complications.  

D, Rule 506(c) and advertising techniques, persona development, deal structuring, etc.  

Investors who have tons of experience still run into massive complications with the process.

(A variation of this, assuming you can buy the note, is to have the property quit claimed to a throw-away business entity with liens attached, and then foreclose, which avoids complications with the current owner.)  

If I am able to get a HELOC from both properties, (I know you can only take anywhere from 80-90% out, so that would give me around $105,400 as a HELOC) and I have the difference of cash ($194,600 if I was basing it off of a $300K purchase price) from a private money lender, can I pay all cash on a property using three different payment types (2 HELOCs and the rest from the private lender) Or does it get complicated when you try to use more than one way?

Depreciation gets a little complicated.