[otrs] Available tickets and acticle actions

Hi, I have two confusing questions: 1. Some acticles could be printed, forwarded, bounced and split, but some could only be printed, forwarded and split. What kind of acticles does not have the bounce option? 2. We have 5000 tickets in Junk quene, but only 1200 of them are available, why? Can we set the available value? Thanks, Arlene