Interesting to see the diverse spectrums of interpretation.
It's hard to give a clear set line as to what's cheating or not. I will hug my friends, both male and female friends. I will hold hands with both male and female friends.
Although most the time I hold a male friend's hand it's to make him (any extremely homo-phobic) person feel uncomfortable. I will say that I'm a heterosexual male, but in regards to basically anything shy of kissing I don't have an issue doing, especially when it comes to messing with my friend.
I flirt, it's what I do. I think that flirting is part of social interaction. Flirting is a means of complimenting somebody, and in a way that's often better received.
For the most part, I agree with the statement of whatever you wouldn't tell your partner is cheating.