Voicethread help

Hi. Is there anyone out there who can help me with these three questions about VoiceThread? I'm ready to start using it, but I need to make sure I have these three things covered before I launch it. Here are my questions: 1) With comment moderation I know I can moderate comments made by students to my post, but can I also moderate comments made by students on other students' posts within the class? 2) Students don't need an email to join as part of a class on EdVoiceThread, but can they still email links to their voicethreads to other people? Could I set it up so they could only be emailed to me? 3) Can you close the voicethreads to all people except the class, or do they have to remain open to every class registered on EdVoiceThread? Thanks to anyone who can help.