You just need to ensure you have a great property mgr and to ensure all your reserves are there above a cash flow for you.

Mortgage brokers have a network of banks they work with and is the most efficient way of matching your situation with the right lender.

Together, we negotiated favorable terms with the seller, ensuring a beneficial deal.

My initial thought was to go back a re-negotiate a 6k contract price with the seller and the end buyer would take care of the back taxes once they purchase the property however it sounds like the title company will ensure these taxes get paid.  

As much of a broken record as I may sound, I can't stress enough how important it is to take this to accountants & financial planners where you can divulge your entire financial situation & they can layout multiple tax-efficient solutions.

It's the most efficient methods for finding motivated sellers.

Perhaps it makes sense to consider a blanket portfolio loan to efficiently extract what equity I can, then set up a separate line for emergencies.  

What's the best method to acquire rental property using OPM and the most efficient strategy to pay it back?

It is not the last months rent, it is a deposit to ensure they leave your unit in good condition, not incase the decide not to pay rent.

The requirement is to ensure the financing is compliant and to do that you need to understand not just business law and RE law, but also financing laws.