Cash for keys is definitely the best way to get people out in the day when I was very active at court houses steps cash for keys was by far the best way to get folks to move and bad tenants in a state with bad eviction laws to me would be the preferred method. you simply pay them when they are leaving the house not before.. that works fine and you give them more than 1k .. you make it worth their while..

It was a 1962, ranch-style house with blocked galvanized pipes and a busted water heater!

If I were in your and/or your mother-in-laws shoes, I would go to a local bank and use the free and clear house to secure a $150K+ line of credit. 

Many successful investors started small, such as with house hacking or buying affordable properties to rent out.

FlashlightTape measure/Laser measurePaper/Pen/iPadBinocularsReceptacle testerLevelMarbleDroneRespirator/Face Mask/Eye Protection/GlovesAQI testerWater pressure gaugeThermal cameraEndoscope cameraKnifeI bought over 20 houses in my lifetime and I’ve never taken more than a flashlight. 

Mike Lambert above is correct about house values in Japan.

But, it may not offer the ROI as other locales, and it may not be "fun" like buying in a favorite vacation spot.2 - The highest ROI folks - Self explanatory, will go where ROI is high and/or regulation low.3 - The second home/retirement minded - These people are looking for minimal ROI but want the house in a specific location because they like to use the property and want it to pay for itself.

When you say as long as its not directly in flight path, meaning - when plane flies over the house?

Networking,  is mostly with rehabbers in the group that we sell houses to. 

Any one of us could give you our two cents on the math of it, but only you can decide if it makes sense based on what your specific goals are. personally, i paid points on my house because my goal was lowest possible monthly payment.