All while wasting some of the lowest interest rates in history and missing out on the time value of debt paydown, cash flow etc.

You do not have to accept the tenant they bring you, but if they move out you have a legal obligation to mitigate (minimize) your losses.

Make 12k a month but have 4k in debt with the rentals being 3k of the debt.

The loans are based off of the property debt service which will determine the LTV range allowed up to 80% of what the property qualifies for.

I have always been a big fan of personal finance and used Dave Ramsey’s plan to get completely out of debt (other than my mortgage).

I am currently inclined to buy another one as the HELOC interest is 100% tax deductible hence I may keep it as a “never ending” nor growing debt. 

I am currently inclined to buy another one as the HELOC interest is 100% tax deductible hence I may keep it as a "never ending" nor growing debt.

This gives her legal capacity to sell. 

Would like to be able to tweak appreciation, interest/debt service, operating costs.

Getting prequalified should always be the first step though, you can just ask the brokers for your max budget based on your income/debt, and down payment size (20% down if you’re going conventional 30 yr fixed, plus ask them what they want to see in reserves after close.