Place yourself on a schedule to paydown principal (no interest only loans). 

Principal, interest, tax, insurance, maintenance repairs, capital expenses, utilities ( if there are any the tenants won't cover), vacancy.  

I debate to pay more on principal on the rentals, as i have always heard re investing is the way to go.... 

Mortgage it subject to bank limits and payoff duration limits, and use that full loan amount (loan principal is free of income taxes) to do another project.

The principal left on the mortgage is roughly 390k and the forecasted appreciation value for next year is over 500k.

this is a newbie question but here is my background...I have been a silent partner in flips for the last year on two properties which will be getting the principal and profit back soon as they are under contract or have sold already.   

I was going to put down 5k on that principal for the future refi. 

What is the benchmark for  cash flow which i believe is all income - expenses including the payment towards your principal in the mortgage ?

Since if they activated the rate rise, it start over on the new principal amount, raising it 2% instead of 3% still guarantees my payments go down instead of up.My other lender is a local credit union and they offer 15 year fixed notes.

Profit in real estate comes from cash flow, appreciation, and principal reduction....use IRR to calculate profit.