For Part 2, I have a repro case in 4.9.2 using the Third Person BluePrint template.
In the ThirdPersonExampleMap select the stair static mesh, Add a static mesh component using the stairs mesh, move it to the side. Then launch the game in 2 player mode with the output log visible. When one of the character steps on the added component you should get the spam log.
2 pictures here to show procedure and results :
