In regards to the not moving a seat if the device falls down below it... There is a picture that has just been shared internally on Yammer of an iPhone, well, parts of it, that were retrieved from a CW seat on the A380 after it was dropped down the side, and the customer decided to move the seat instead of telling the crew.
It is about 20 parts and completely mangled. Yes, the risk may be low of it starting any sort of fire, but the risk is still there.
I won't copy and share the picture, as I don't want to get into trouble again, but it is very real.