Is bizz done this way on DSCR loans or No. ?

What type of loan are you looking for ? 

It's going to be very difficult to secure an investment loan on a STR with bad credit.

I'm sure my cash flow could vary based on the loan I would receive since I could use a first time home buyer loan but lets assume that I use a 30 year fixed FHA mortgage at 7%. 

If your rentals have a small loan amount remaining and you still have enough spread in between from your current loan amount to the loan to value and if that's enough money needed to fund your next deal then the Heloc will make sense for you.

In addition, owner loaned us $100,000 at 6% simple interest for one year to make major repairs (installed heat pumps, replaced boiler (for heating water only), replaced some siding and major roof repairs.)We were very clear with each other what we each wanted out of the deal.

The leases end in October and August, so if I were to buy it with a loan I would eat a part of the mortgage for four months on one property and six months on another.

I know I have other options like selling the notes or partialling, but this question is more focused on taking collateral based loans against the notes.

Please tell me where interest rates will be when you finish your construction loan and need to put in permanent financing?

This would be a land development loan.