I would suggest, as a first step making sure to stay in the loop, get in touch with the director. Touch base about the conversations that they have had with the artistic director so far, making it clear that you just don't want to let things slip through the cracks. I'd also suggest having the same kind of conversation with the artistic director, making it clear that your biggest concern is knowing everything that is going on related to the production. Getting him to not do your job for you over the long run is a little trickier. I'd start by trying to get him to understand that information from conversations that he has with individual directors (who may be friends of his) about things like schedule, the set, etc. needs to be passed on to you.
About the production meeting....assuming it cannot be changed because of other people's schedules...I'd suggest that you think about questions you might have that could come up, and share them with the director when you talk to him/her. Then, schedule a follow up conversation with the director, and go over those questions, to see if they were addressed at the meeting, and if there was anything else of import that they would like to share. You could also try sending your inexperienced assistant, telling her to just write down everything she hears...