Usually "hell of a..." means 'very', or 'exceptionally'. It is used to add emphasis, either good or bad. "That was a hell of a party last night" - It was a very good party last night. "That was a hell of a thing to say." - It was an awful thing to say. If I just said "It was a hell of a thing.", it would depend on the context as to the meaning. However, if I guessed, it would mean that it was surprising and possible shocking. "It was a hell of a thing, her old boyfriend showing up at her wedding."

Yes. For instance: "That is one hell of a motorcycle you got there!" (It's a badass motorcycle) Hear it often used to describe something powerful, cool, tough or difficult. - Christoffer^^