Hello @user31828 ,
At this time there isn't anything inherently setup for assigning tasks to certain account users. It may come down to naming the emails (email names aren't subject lines so contacts wouldn't see them) with the "assigned" user's name included, and then messaging them that they have a campaign that needs to be done by X date and/or time. You can also utilize the calendar view to show when emails are supposed to go out, but won't actually be scheduled until explicitly done so.
The lowest permission level user - Campaign Creator - can't actually publish, schedule, or send campaigns, so the "moderator approval" aspect would come from the owner or an Account Manager being the ones to do the publishing/scheduling/sending. Beyond that, there isn't a moderation approval system within accounts at this time.
See also:
Add and manage users in your Constant Contact account
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