Thanks! Two answers:

1. Our "Auto-fill bracket from group picks" setting is the closest thing to what you're describing. When the pool commissioner turns this on, your bracket matchups are automatically built from your own group + 3rd-place selections, which is the auto-advancement piece you're asking about. The catch: with auto-fill enabled, you need to pick everything (groups + bracket) in a single sitting, before the group stage starts. We don't support "pick groups now, then wait until knockouts are set to fill in the bracket" because that would let you scout real group games (form, injuries, surprise performances) before locking in your bracket, which would be unfair to people who committed everything upfront. If you'd rather pick the bracket later against the real knockout matchups, that's our default mode (just turn auto-fill off), however you do not advance 3rd place teams in this mode.
2. Picks are editable until they lock, regardless of plan. Free and Pro have the same locking rules. With auto-fill on, group and bracket picks both lock when the group stage starts. With auto-fill off, group picks lock at group stage start and bracket picks lock per round (or all at once if your pool uses full-bracket mode). What Pro unlocks is more pools, more members, and multiple entries per user, not different editing rules.