Two queries reg ticket status changes and ownerships

Dear all,

 I have RT3.6.0 running on AS4. There are two problems i hope

someone could help me with.

  1. How do you stop ticket requesters from accidentally opening their
    own tickets? The situation is that user creates a ticket and then
    after ten minutes sends a mail back when he gets an autoreply that
    there was something he forgot to add. Now the status of the tickets
    will be open with owner as nobody. How do i stop open-nobody tickets.

  2. Sometimes i find that some consultants accidentally changes the
    status to resolved or rejected without taking them creating
    resolved-nobody tickets. I do i prevent this?

It may be something to do with the rights we give to owners requesters
and groups.
Any ideas for me?

Thanks and Regards
Sujith Emmanuel