1)You can tip, and I do always tip staff at a barbers/hairdressers, and provided the food and service were at least alright, staff at a restaurant; but it seems that it is a lot more discretionary here than in the US; you'll find prices are probably higher here partly because service industries don't assume tips.

2)Varies enormously, and not just "you get what you pay for"; you'll find dirty, cheap establishments where the people are friendly and the food is top notch, and vice versa. It's a matter of finding places you like. Again, as a customer, you're free to act as you like, I'd like to think that most of us are polite (I'd imagine ingratiatingly so to an American) but of course there are bad eggs. As for waiting for service, we Brits just love a nice queue.

3)You can wear white socks. A pikey's a pikey for other reasons.