If a girl has a different style in their hair every single day I think it makes them look high maintenance. For your every day look you should just do something simple but still pretty and then on the weekends or a special occasion you can do something more fancy with your hair and the boys will go "wow!"
Doesn't really matter. I don't mind if girls do their hair differently now and then but you don't have to change it every day. Wear it out or in a pony tail. Or just keep it the same if that's what you like...pony tails are cute tho :)
I don't think it would matter. I style my hair pretty much the same every day because it looks the best and doesn't take a lot of time to style and I still get compliments on it. I don't think that changing your hair every day will get you a new guy and I don't think that never changing your hair will cause him to leave. Do what you want.