Focus on making sure you can answer all of the FTS (FileMaker Training Series) questions at the end of each chapter. When you take the test, think about what answer is the best answer that someone at FileMaker would think of. There are some notoriously tricky questions on the test, but I've now passed the 11, 12 and 13 tests. One good tip is to take both current test releases (12 and 13 currently) within a few weeks of eachother as there is similar topics covered by both training series.
To answer your questions:
1) for license I'm assuming you mean certification, yes, there is only one certification for each edition of FileMaker. The certification covers the entire product line.
2) All topics covered in FTS are on the test, and are part of the certification.
3) You are correct, everything in FTS is covered.
4) FileMaker Go is covered as part of the test as well. The test is for the entire FileMaker platform, not just individual sections.