You might want to also do some research into the app store's for your respective targets. I might be wrong on this but from my understanding apple's app store only allows Objective-C written apps while Google's play store prefer's maybe even requires Java written apps.
Beyond that cross platform hassle's always occur, you will need to gain access to the device specific rendering and input API's either building your own mobile engine of sorts or using something pre built. There are many options for this however most are Java or HTML5 / JS related. I'm sorry that I'm not answering your questions but I would suggest that you research in to what technologies are available for cross platform development and what will best suit you and not focus on the fact that you want to use C++.
From just some quick google'ing it looks like OpenGL ES is mainly an iOS thing, I can't find any reference of it's usage on android devices. Android does use open gl and here is a reference page that should get you started (directly from the android developers network)
Here is the apple reference for using OpenGL on the iOS platform (which does make particular note of the ES flavor)
Box2D on iOS...
Port of Box2D for android (it's java...)
If nothing else these sites should get you started understanding the differences between the implementations of these technologies on the two different platforms.