I dont understand why CoC doesnt include the principal part of the mortgage payment.

You’ll need to borrow money from a lender to acquire the property (it’s not all investor money).  

You would get equitable ownership into the property, but seller would be on title (just like any other mortgage until the balance is paid off). 

I would start speaking with lenders about your plan to get insights on how the logistics would work. 

I kept meaning to buy for a few years, but I’ve been simply overloaded with a startup.My current country prevents me from purchasing property (non-citizen), and doesn’t offer fixed rate mortgages - the floating rate is high rate at 7%, and has been about this the last 20 years.

I would suggest to connect to other local investors as much as possible to network, educate yourself, make connections with title companies, contractors, wholesalers, hard money lenders etc, those will prove vital to your success.

Always good to ask your lender.

As a private lender would you pay the full 100%, or still do 75% Loan to Purchase price and have borrower put money in?

I have a free and clear, rented property I intend to keep for now, but want to get a loan to pay off another property's loan to 1031 it with no mortgage balance. 

Despite higher interest rates for the mortgage (7.625%) and the HELOC (9.5%), we are still positive cash flow.