Yes the price includes all air travel.
The best advice I can give you is to refer to the CTC thread in this part of the forum. It has a wealth of knowledge from which I referred too, and it helped me prepare for the selection.
Language shouldn't be a problem at all, your English seems perfect to me from your writing. I believe they will require you to pass an English test but I would imagine that this is very basic and you will fly through!
Best of luck in the future!