To answer original question literally:
Joel Tudor says it only counts if you are hanging ten (in Wingnut's art of longboarding 3, you can find it on youtube).
In competition you get scored for hanging 5 as well generally (except that specific hawaiian noseriding contest already mentioned where you can be anywhere up to 2 ft from the nose).
As for worrying about the crowd etc. it's the same with every manoeuvre in surfing; you have to learn it first when there is not someone to crash into (uncrowded spot, early in morning), then once you can do it you can practice in crowds but it is a scary transition. As will smith said, god placed the best things in life on the other side of terror!
Go on waikikichan's website it has a few great articles on how to cross step. Go on noseriding.com too.
While we are thinking about "what counts", it pretty much doesn't count if you don't cross step! Good luck!