The ability to set up a channel for clients to use via invitation. Where they can track all of their engagement in one place and respond is needed.

Instagram being part of that group of websites as well.

I would also (if you don´t create an app) like to be able to choose which social channels go into specific Slack channels.

Please also include filtering and choosing how many messages that will be imported to slack. As well as adding showing which FB page the comment comes from.