Channels and private messaging: You can use IRC. It does that very well. (You don't even need a IRC client or any other specialized software; you can just telne

Channels and private messaging: You can use IRC. It does that very well. (You don't even need a IRC client or any other specialized software; you can just telnet in and that works, and it was actually designed to be able to work without specialized software. However, using specialized software is better because it can auto-pong and can prevent what you type from getting mixed up with what someone else types.) Share images and files: There are many ways to do this and it can be done independently of the chat system in use. (However, it would also be possible for a IRC client to include such integrated features, sending the URL so that other users can download whether or not they are using the same software as you do.) Support for some of the automated commands you can integrate with Slack: Unfortunately, I do not understand.