I don't even know how the flippers buying them are making money.  

They only put liens for the money they pay for boarding it up and mowing.

If you have the time and experience, hiring your own subs (like plumbers, electricians, painters) can save you some money, but you'll need to manage the project yourself.

The better you manage your investment, the more money you will have to maintain the property or save up for the next investment.

So if I “lose” money investing after depreciation, expenses, mileage, then we get a tax refund because it offsets my husband’s salary.

He's my friend too so he Venmo's me money.

Minimal cash out-of-pocket, ($800), no banks, no hard money.

It's in a part of town that is being revamped from former industrial to nice stores, shops, restaurants, and businesses and I believe there is even some money offered to help revamp that part of town if you purchase something and help improve the area.  

Cashflow, appreciation, somewhere to park money or other?

On the other hand, you are risking the money and that's worth a lot.