Yup that's all it does, automate those best practices, so there's probably no need for you to use it over CloudFlare.

GAE edge caching is poorly documented, here's what I've found so far:

[1] https://groups.google.com/forum/#!topic/google-appengine/6xA...

[2] https://code.google.com/p/googleappengine/issues/detail?id=2...

[3] https://groups.google.com/forum/#!msg/google-appengine/8QgEU...

[4] https://groups.google.com/d/msg/google-appengine/8QgEUBOiNFw...