Good or bad?

Not really. If needed, they can always give you a wig (there are some that look REALLY realistic, for both theatre and for film.) If it was ABSOLUTELY necessary, they may ask you to cut it, but they probably won't. So I wouldn't worry about it :)

hm....in some ways i think it could make it harder, in the case that your character is completely average and your hair would mess that up....but i also thnk your hair could be a big help to you. it might help you to make a lasting impression and it might help set you apart from the rest.

Um, I don't really get what you mean but I think long hair could be a disadvantage as it could get in your way, easily get caught in things.
But if that's how you want your hair then keep it, just figure a way to keep it out your face, like in a bun or something like that.

it completely depends on the type of parts you want and how the director envisions the character. the only way it would be a disadvantage is if you completely refuse to cut your hair for a part.