At the moment there is no PDF manual. The only official documentation is hosted at http://doc.mapeditor.org/ and available from the repository in Markdown format.
I still need to spend a lot more time on updating and completing the documentation, and will consider doing it in a way that also allows PDFs to be made available. Probably it means using Sphinx instead of Markdown, for example.
Regarding a 2D game engine, I would suggest picking one of the following depending on your taste of programming language and target audience: