This means you need to study hard.
I know some books.
"The Study of Counterpoint" by J.J. Fux, translated by Alfred Mann, it has parts of the 'Gradus ad Parnassum' work.
Its the text alot of the great composers read. It is very plain, well-structured, and short.
If you want alot more examples you can get "Counterpoint in Composition" By Salzer and Schachter. It covers the same stuff, the five species in more detail. Plus it talks about using it in actual compositions, prolonged counterpoint, Schenkerian stuff. Its alot bigger, more pages and more expensive.
A species is just a set of rules in which you practice counterpoint.
The first question is explained here:
All the questions about 'species' are explained once you learn all 5 species and thus learn counterpoint.
Tonal cantus firmur means a major or minor one. I recommend doing a major one, cause its a bit easier. Back in the 16 century they used to use modes too. So it means, not using modes. A cantus firmus is a whole note melody you write counterpoint against.
I am not sure... you want to skip those lessons? If you, then that answers question six. If you want to learn this, follow those lessons. If you don't want to learn academic music theory then quit and focus on politican science or something else.
Really, skipping those lessons is not a good idea. If you want to learn to compose or learn more about music you need to practice counterpoint, even if you thing its boring. Counterpoint is everything.
Also, J.S. Bachs works aren't good examples. Because Bach breakes the rules way too often to get a good impression of the rules. For example all the fugues in WTC I and II are 'wrong fugues'. Of course they make good music. But at this point they are not good study material. They learn you how to break the rules and how to actually compose real music. You need to learn the blunt rules of species counterpoint first.
But, if you have to do this exam and you don't know the stuff you should. Pick the first one and try to bluff your way out. Make sure you have the bare essentials. Make sure it is clearly a three part counterpoint exposition. And then bluff your way through the actual counterpoint rules by claiming you broke the rules because you like it that way.
In the other two every broken rule can be considered an error, in the first there is a bit more room for discussion.