I with you : Pebble!

First of all, you must to understand what are the differences between each architecture. Second, what do you want to build? What you need to have in your App to have a good MVP (Minimal Viable Product) ? Then you should focus in what architecture you want to use. Good luck!

You should take a look at the Fragmented Podcast. The latest episodes is about 10 Books Android developers should read .

Yes you can use! You only have to change the rules from your database. It must be read and write == null. Everything will work just fine!

I'm using it! It has some amazing features! I hope that the project keep going, and with amazing new features!

In my humble opinion, there is only one factor that could make an app become a hit. It's the population will receive the app. It does not matter if it is well design or even have a solid structure running under the hood. Let me give you an example, here at my country, Brazil, a few months ago a app received more than 200K downloads in a few days. The app has only one Activity, and it is poorly programmed. All the flaws are clearly visible, but the app become a hit here. Most of my friends had the app installed because was fun making the weird noises that come out from the app. (The app name is Vem Monstro!). To sum up, there is not a key to success in the app world. Sometimes, you only need to have a good ideia, and timing.