Regarding 3:
I am not a developer but how hard can it be for God's sake? This has worked for desktops for ages. Of course, if your device is low specced, you should not be expecting to run the latest games. Other than that, with 2013's developer tools and knowledge and whatnot, scaling to a couple of resolutions and a couple types of devices shouldn't be that big a problem.
A couple?
http://gizmodo.com/just-look-at-how-much-worse-android-fragmentation-got-l-921423675
(That was just a joke. Obviously every different device doesn't introduce fragmentation.)
But it's silly to downplay the real problem. This isn't only about screen size and processor speed. Android fragmentation has many different levels. The biggest is simply version fragmentation. Developers can't just target the latest APIs, they have to go back and support significantly older versions in order to address a majority of the market.