Yes! I brought a picture from a celebrity magazine to my hairdresser once. She did such an amazing job and the haircut ended up looking better on me than on the actress! Go for it!
Of course! I actually brought in a picture of one of my friends friend! Haha, no one knows... but I really liked her hair, and it lets the stylist see a visual instead of explaining to them, cause they might not understand what you're trying to explain. I do it all the time