2. Yes, it is very competitive. My app has dropped from the #8 spot in iPad/Free/Music to the #41, and it's hurting. :-) It has done very well in east Asian markets though.
3. Not sure. I might try to add some viral channels in the app. Otherwise, I'll have to slog it out, and get to 10M+ the slow way.
4. Specific goals is more or less a hack / dangling carrot. It's hard to say, "I'll succeed when I succeed." Two years ago, my specific goal was to launch a single app. This January, my goal was to make revenue. Now that I'm making some revenue, my goal is higher. Maybe when I hit 10M, I'll want to hit 100M? :-)
5. No, I'm not a musician. That's why I built the easiest piano on the App Store. :-) If you have an iOS device, download it and let me know what you think! http://itunes.apple.com/app/id477014214