HELP cartilage piercing problems!?

I've had my cartilage done for nine months now and I was wondering if I cud take the stud out with out it closing? And how many hours can it be out? I haven't taken the stud out since I've have it done and there's a bump on my ear under the back of the stud, any ideas what it is, if it's really bad, and if it will go away??? It's been there for quite a while... And when I change the stud any recommendations on new ones?? Like gel barbells or rings?