Like i said, I don't consider this a bug. The button is supposed to subscribe/unsubscribe all channels and after that, your custom subscription settings are re-applied. This is not causing an issue for the user.
I am unable to reproduce this. Might be a side-effect of the broken tile implementation in the first beta build and things have been cached by your OS. make sure that the tile images are located in the gfx directory of the TeamSpeak Client installation. Also, make sure they do not exist in the gfx directory of your config path (%APPDATA%\TS3Client\gfx).
Thought about changing is there too, but I think it's ok to show the tags in the chat since you might need a location to copy & paste the channel name. Currently, I'd prefer to wait on user feedback once the stable version of the client is released.