I can easily afford the NOLA mortgage while living there but was hoping to rent out the property after the project is completed. 

Owners haven’t paid mortgage in 4 years.

If I use seller financing to own a property, do I build equity even if I sell before the mortgage is paid off?

The most obvious is that you will be able to offset your mortgage with renting out a few rooms.

We're a local lender and we have a bunch of newer investors who are also local.

Open to loans but only if we net 10k a month after mortgage payments

How can I negotiate to buy a house that didn't sell at $749k on the open market, subject to the existing mortgage with cash over, seller pay the broker fee and i buy "as is, where is"?

Whenever you get ready for financing give me a call i'm a veteran and mortgage broker i'd love to asssist you.

But if it's priced a little high or the listing is a little funky there might be a way to get them to look at your offer.You might offer your price as cash plus a small second mortgage to them as owner financing. 

If this tenant doesn't move out, I risk postponing the close date, and losing money on the mortgage every month this situation drags on.