A signed lease is a legally-binding document.  

3.Any tips for managing cash flow and leveraging existing assets to keep growing my portfolio?

Make sure to follow all legal procedures correctly and keep documentation of all communications and actions taken.In the long term, taking preventive measures from the start can help avoid similar non-payment issues in the future.

While going through the HOA document I saw that the HOA secretary and president are from the company that purchased the complex from the original developer.

That said, we do lending out of our SDIRA and there are some considerations about prohibited transactions and set up (checkbook control or custodian managed, for example) etc. that should be reviewed with a custodian or SDIRA expert.

Who can provide a referral or insight on managing this rental?

You are a beginner in REI – so get started first, accumulate some equity, get some serious cashflow going, get some experience with managing real estate, figure out you want to do this long term…and then worry about how to layer an LLC cake.

We use QB for accounting and Rent Manager for PM (I often feel like it uses us - although there customer service reps are great).

For a section 8 fund also ask about there experience in owning and managing section 8 housing as if it is not very hands on, it will not end well.

I would really recommend you hire a property manager.