There's a option when starting a conversation with someone to allow participants to invite others to the conversation. If the conversation starter doesn't want this, then you won't be able to invite other people. While the conversation system has good points, I really do miss the option of simply being able to forward stuff. Very much agreed with you on this, particularly on the second point.
I'm not really fond of the new 'online indicator' on the topleft on avatars, I hope this won't replace the "Online/Offline" we have now. Also, I doubt I'll ever see Kat "Online", or many others of Staff. Why not hide it for those user groups? Or only show "Online" for every user (that's online)?
This was something that came with the XenForo 1.4.1 upgrade we did last night. They did not have an online indicator before which was why we were using an add-on for the online/offline banners. However I personally feel that the green corner icon is nice and subtle, so I would be inclined to keep that and get rid of the banners, I also personally think that if somebody is offline or appearing offline then they don't need a banner or icon to show that. (Basically the green corner icon does what you are suggesting).
I do not think getting rid of the banner would be a good idea. I'm not sure about others but me personally, I rely on the banners especially for character issues or when dealing with PMs where the user may be waiting on the forums for a reply. With the green indicator on the top left of an avatar, I would frequently miss the user's online status. Regarding staff being invisible, I don't think that's a reason to customize the theme and remove their online status banner. They always appear offline. So?
I much prefer the banners to the little green indicator. However, they perform separate functions. The small green indicator is there to show your current activity, ie whether or not you are actually reading the thread/post in question. (Chok has just informed me that this is incorrect - guess I misunderstood the explanation in XenForo's videos! As for the online/offline banners - I'd love a purple one that says "Ninja Mode" for invisible mode, but I think others might object! ^_~
would it be possible to add a server status to the forums? kinda like the one on the index page but for here. i know its not a huge deal/priority, but i think it would be nice for the daily forum users.