For a single home the fee will be very minimal. 

However, the advantage of the commercial loans is that closing costs are a lot less so the am length is really minimal. 

What would be our best option to minimize out of pocket expenses on the deal?

Are the returns on the duplex minimal and could you get a better ROI elsewhere?

You can contact the local housing authority to see if the voucher can be used as any leverage, but you need to keep in mind that a.) you will likely never collect the money if she moves out, b.) your prime goal is to get the tenant back on track or to get possession of the property back and minimize your losses. 

While in theory this looks like a great plan, the key in execution would be the balance between renting for your target price, and ensuring the vacant unit rents quickly to minimize holding costs.

For example, if the lien in second position foreclosed you are buying subject to the first lien...you have to know how to verify all this information.I would find something in your area that needs maybe a minor rehab that you can BRRRR or house hack to start with to minimize your risk. 

I went over, but it was on items that add value and will minimize my maintenance calls for years to come.

It seems to be just daily foot traffic, minimal to no gouging of the floor. 

They essentially did a bunch of showings back to back for an hour to minimize impacts to the tenants.If your tenants give you a lot of push back it might be difficult depending on the verbiage in your lease.