#1. So rare it wouldn't be a recurring problem. Regardless of nationality, I would expect that every person on an airplane should respect personal space. Like Doc Savage suggests, a request might be appropriate, but then contact a FA and ask that the person remove their foot.

#2. It happens. Pack anything valuable in a protective device. Laptops should be in a sleeve then preferably in a hard shell case. Don't assume that everybody else will be careful to protect your personal items, and you should assume that other people will act selfishly. I know I travel with the absolute maximum of precautions, but don't assume other people are going to be nice and not toss your bag around. I once witnessed a younger lady tell the FA that everybody had to take their bags out of the overhead bins because she had a very valuable dress which she said it was more important to protect than everybody elses cargo.

Chuck