The away feature can't be done because no message is sent by the IRC server when someone sets themselves away, so no other user except the one who has set themselves away/back knows that their status has changed. If you want this to change you'd have to talk to an IRCd developer, even then it would be a long time (if ever) before this became standard in many IRCds, and switched on in server configurations.
As for the multiple user chats, isn't that exactly what a channel is for? If you want to talk to several people at once create a channel for them, make it invite only if you don't want anyone else coming in. It's a lot more bandwidth efficient than if an IRC client tried to emulate group chats.
