>8, 3, and 3

Very big split! In one past case of mine, I found the higher-rated one sneaked their rating down to go along with the group without saying anything. Hope that doesn't happen for you.

>I'm curious if reviewers can update their score freely during the discussion or they can only update once at the end

AFAIK they can change at any time by "editing" their original review comment. Ideally they also add some text/reply to indicate that they changed their score and why.

Whatever the outcome, congrats on your first submission!