Lennar Mortgage which now offers DSCR loans.

I'm assuming you would need to seek a whole new loan?  

Loan Buy Down4.

I also found a bank that would finance that low cost of property as a regular 30 year loan so payments on debt is way low obvious $100 - $120 per unit.

When you go to refinance into a long term loan your personal credit score will 100% matter.

When we moved out, the landlord insisted on keeping the entire security deposit of $1,000. 

Since the sellers are opposed to seller financing, consider exploring alternative financing options such as traditional bank loans, private lenders, or hard money lenders.

you can do a bank statement program for a 2nd but the easier route would be to do a foreign national DSCR cashout refinance loan 

I’m an investor in The Woodlands and a mortgage broker.Whatever you decide, great job securing a house with such a low interest rate and good luck!

Additionally, you'll need to locate a property with either a vacant unit or a shorter lease that could be canceled, allowing you to occupy a unit as your primary residence, as required by the terms of your low down payment loan.