Ideally, you would have money for down payment in savings and use a HELOC to find the rehab to reduce your hard money costs.

My plan is to self-manage the property and rent out the duplex as an STR.   

I self manage my own rentals and I also operate a management company assisting other investors nearby. 

Subject too you can get in low cost or free but the risks associated come with the need for money, silent seconds can ruin your personal life and make refinances possibly impossible or can sink the investment throughout or after liquidation.

Tenant shall pay for all costs associated with remediating pests from the Premises and shall inform Landlord at first sighting of any pests in order to avoid any infestation of pests.

I'm trying to find a property manager that handles mid-term rentals and will also need help with furnishing the properties.

You need to get a quote from a local handyman or contractor.Not sure about every state, but in the states where I invest - If you do the work yourself you can only deduct the cost of materials.

Last night, I learned that there's a problem with the home: during the inspection, six gas leaks were identified, and repairing them will cost approximately $7,500 in labor and materials.

These areas you are describing rarely appreciate, so the pricing is low and you can cash flow, but, as I said, at the end of the day, it is very hard to manage these types of properties.

Most investors opt for the skeleton versions that truly miss the mark and lead to convoluted amended and restated agreements that cost far more to correct than simply paying for the agreements to be drafted by a professional at the start.