Well, I list all those platforms, but I'm only actively developing with Android in focus right now. This is due to the ease of access for emulation and development. Apple want me to have a Mac to give stuff to their users for free.
Don't worry, I've set up the project so cross-compatibility is not ruled out in the slightest down the road. I think. We'll see.
I probably can't answer it. The project is still in very early, pre-usable stages as of now (14/10/16).