Disagree on #3. Social & collaborative features are the bane of my existence. No I don't want to share all my scraps of information, no I don't want to let my friends know what I'm listening to, no, I don't want to publish product purchases I make to twitter.
I think a better #3 would be: decide whether your audience is individuals or businesses, then build for that.
I think a better #3 would be: decide whether your audience is individuals or businesses, then build for that.