Re: i. THE TRIAL
Edmund is staying close to Susan (and Lucy, if she's there), except when one of them is testifying. He will try to look supportive of them and the other witnesses.
When it's his turn to testify, he'll identify the wand and how Jadis has used it in the past, since he's one of the few eyewitnesses to her turning someone to stone without actually being a victim himself. He'll explain as much of his history with her as necessary/he's asked about. It will be factual, and he won't avoid anyone's eyes or actively seek them out.
He is absolutely watching Jadis's reaction when she realizes she can't leave the box. He will kick himself later for not watching the dwarf.