I have never been asked what my short or long term goals are, so I am afraid that I do not have any suggestions for that part of your post.

When asked why you left your last job, I think it is alright to simply state that you had gone as for as you could and, since there was no longer any chance for personal or professional growth you decided to pursue other avenues for employment.

I don' t think saying that you needed a change is the best idea.Or that you had been there too long. I would think that this would indicate to interviewers that you are easily bored and just want to get things over with. While on the other hand it may also indicate that you need to feel challenged and the challenge just wasn' t there any longer because you had become so good at the job.