When you have a duplex and tenants on both sides stay for ten years, it almost guarantees that something isn't right.I would study your market and determine the value of your rental, because I bet you are losing money every month.

If you're looking for the cheapest route, conventional may be a better bet.

You can just answer it without the jazz, and I bet you know a few places right off top of head where people WANT to live, right. 

We purchased our laundromat in a safe, middle class neighborhood.

Kodak was a industry "beast", a definitive "safe" investment, until it wasn't, and it went to trash in a flash.   

I bet that you can pay off this debt in 1 year or much less.

Personally, if your market tends toward the former condition (better/normal appreciation) I think it's a fairly safe deal looking at the long term, assuming infrastructure around you continues to support the idea of renting it.

I haven't seen any statistics to this effect and I don't think any has necessarily been compiled but I bet I wouldn't exaggerate if I state that 95% of the value of real estate in Southern Spain or at least the province of Andalucia is in the Costa del Sol.

Your best bet is to keep liquid cash and avoid PMI.

I'm reaching out to other plumbers to be safe, but are those supplies mine to use now for the next plumber?