Hi! I've been using InCopy on a little bit larger scale and had a suggestion or two about team organization.
If any of the below are already possible please let me know how to do them:
This is a great program to use and I'm glad i stumbled upon it!!
You’re going to need to look into some third party solutions for all of that.
K4 is one but it’s very, very expensive.
Those are great (and frequently-requested) feature requests. Please add them to http://indesign.uservoice.com (InCopy features go here too).
You're not overlooking anything; as Bob said, those workgroup management features only come with expensive publishing systems. Most of my clients develop their own notification/staging systems using Slack, Basecamp, Trello, or the like, or even a shared Google Sheet that people check off as they complete something. Not ideal but more organized than email.
One trick that may come in handy is for the INDD originator to put a text frame on the Pasteboard on the first spread (or even every spread) and export those to InCopy. Users can communicate w/each other there, even doing sign-offs.