I am not sure about the different mobile platforms and as long as they use opengl for rendering and offer a possibility to compile c++ code for them, big parts of my "engine" should work with them, after some small adjustements, as I wrote before. The only bigger (also not really) problem would be my xml parsing.

My internet is slow, so that already is a reason to use bone animation instead of vertex animations. But as the polygon count is very restricted, that most probably wouldn´t be a problem, but also means that bone animations aren´t much behind in terms of performence.
For now I want bones, but I may add a possibility for vertex animations as well, if bones turn out to not be very suited.

Yesterday I worked the whole day on trying to import a collada file and gave up on loading the texcoords correctly somewhen today...
I now wrote a converter using assimp to an own xml based format. That means, that I will provide a simple command line tool to convert all kind of file formats to the one of my engine.
It also doesn´t have animations yet, but converting files and loading them already works well. I will now go on with the animation part finally .