If you had done the pong tutorial you would know how to render text, using the Label Widget. You could then take a look inside the documents for label to learn how to set a custom font_size.
Yesterday you were arleady referenced to the docs on how to use spritesheets (Atlas), how to do smooth movement (animation), animation frames are really up to you and can be done however. Reading and Writing is a python thing not a Kivy thing. I would look into python's support for json or pickle. The default kivy splashscreen can be changed when building your application for release.
On Google Play it costs 25 dollars to be able to publish.
For game stuff you will probably also end up using many of Kivy's canvas features. Canvas is a method of interacting with opengl es 2.0.
http://kivy.org/docs/api-kivy.graphics.instructions.htmlhttp://kivy.org/docs/api-kivy.graphics.context_instructions.html http://kivy.org/docs/api-kivy.graphics.htmlhttp://kivy.org/docs/api-kivy.graphics.vertex_instructions.htmlThe reason everyone links you to the docs is that it is the easiest way to learn the capabilities of kivy without having to read "20 paragraph blog posts", the docs cover exactly what kivy is capable of and nothing more. It's up to you to learn how to use all the tools that come in kivy's toolbox and then apply them to create the type of games you want.
There are many different ways to achieve most of your goals, especially things like animated sprites, and it's up to you to decide which architecture best suits your game and you as a coder. Also, remember Kivy is not a game framework like Cocos2d, you may end up doing a little bit more by hand than with a framework designed specifically for just games. Many game-architecture decisions that will be made for you in a framework focused on games are left up to the user in kivy. This gives you the freedom to build exactly as you would like, however, with that freedom comes more dependence on your own code and design.
Read the docs, get your hands dirty and experiment with them, I assure you how to do everything is covered in the documentation and tutorials, it may just not be obvious to someone who is learning and not experienced with the framework. Then if you still get stuck places, come to the forums with specific questions and code, it is always much easier to help when there is code with a specific issue rather than wish-lists.
You could consider trying to follow along with the assignments from this Cornell CS 1100 class focused on using Kivy and Python:
http://www.cs.cornell.edu/courses/cs1110/2012fa/assignments/index.php