About points 1 to 3, I think e acknowledged above with enough emphasis my complete lack of social wisdom so far... :(
Regarding 4, just as the app said automatically, I'm also sorry that something went wrong... ;) Can you tell me where, on the flow of the app, you experienced this? I'm on Heroku using their free tier for now, so maybe you just experienced a lack of server resources... =O
1. Add your logo to your Twitter account and get some additional content up there. People aren't going to follow you if you haven't posted anything.
2. Create a G+ page as well.
3. If people are tweeting about your app, you might want to have a running list of those tweets on the front page of your site.
4. Fix the app. I'm getting a "sorry but something went wrong" when I try it.