I love going hiking, which is what I prefer to call it.  Other countries have all sorts of terms for it like bushwalking, which is what Australians call it. 
Yes, I have heard that term.  I think that the British have some slang terms for it, too.  I like hiking, as well.
Yes, it's a popular activity no matter where you go in the world, not to mention all the health benefits of a good walk.