You will now be your own bank, whatever collateral that you bring to the table dictates the amount you can recieve.

Banks and typical lending institutions have a VERY hard time thinking of loaning you money that will be collateralized against an asset that they have no way to collect in case of non-payment. 

I'd much prefer to get a HELOC or something similar as you mentioned, but I only have one rental at the moment and it has only ~15% equity, so not much collateral to offer unfortunately. 

You could not get a bank to loan you 80% of the cost of buying a stock using the stock for collateral and be comfortable the stock will make all of its payments for the next 15 years and be paid off. 

I have good credit and income to debt ratio Some collateral and down payment but I am wanted to make sure I am doing all this rite.

Subject collateral must be in WA, OR, or CA.

. - If the owners don't redeem the property from you after the 3 year period, usually the bank will because the bank doesn't want to loose their collateral over a few thousand dollars in back taxes. 

If you own a SFR without debt and REFI the property to cash out the equity then use the cash to invest in a syndication or buy another rental, is the interest on the loan collateralized by the SFR a tax-deductable expense? 

What happens to the note collateral after I sell the property to the new buyer?

Seller obviously needs some sort of collateral for their security and payoff guarantee.