Wonderful ideas and thank you for being willing to take the plunge! I'm sure everyone interested in joining would be willing to help out however necessary!
Just spit-balling some ideas here:
What about a channel for prompts, challenges, or contests? Like for example if members of the server has interest in doing Sketchtember together, we could all use the same prompt list and post our results in that dedicated channel?
Perhaps a channel dedicated to critique or suggestions? Like a creative advice channel where one could post a WIP and request assistance with the piece. Just so critique stays out of the general art share channel since its not always welcome but sometimes sought after.
And perhaps a place where members can request collaboration or collaborators?