Well, the friends list is in fact your watchers list. You have to add art and then eventually you'll get some watchers. Every group has a "Join this group" button, it could be on a different panel, depends how the group designed the layout, but there are always such button.
Well I've barely even started making it. I'd use it as the main background image of the main screen. The program would essentially allow one person to host a session (automatically the DM of a D&D game) and anyone that joins it would just be players. It'd include a dice roller, scroll-able map, player list with access to character sheets and the like. It's a concept I've had for a long time and just today remembered it when I saw this awesome image Its all good if I can't use it, I'll find another if need be