I feel the social side of spotify is somewhat lacking at the moment. Firstly, I can't connect with my Twitter friends, who, let's be honest, have much better music taste than my facebook friends, who are mostly people from my high school that I never spoke to. Also there doesn't seem to be a way to find anybody that's not one of your Facebook friends. There should be a way to search for people who have Spotify accounts, regardless of what other networks they're on. It seems like the only way to find people is to search 'spotify:user:usernamehere' which isn't really the most intuitive, and requires trial and error to guess what their username is.
I think the 'People' tab should show a list of people that you're subscribed to, with a stream of activity showing playlists they've made, albums they've listened to etc. and perhaps the ability to post statuses: recommending songs to your 'followers'. Which brings me to another point. There doesn't seem to be any way of knowing who is subscribed to you (as a user, not just a certain playlist). How many 'subscribers' do I have, and who are they? I guess some of these features may be in there already, but if they are, it's not obvious or easy to find.
I think these features would really help make Spotify more engaging, which would be useful now that Rdio is a competitor in the UK, and does social things very well.
Please just post 1 idea per topic, otherwise the Spotify moderators don't know for which ideas the kudos are meant. The 2nd part of your idea has been implemented in the newest version of Spotify.