1. Is it ok to use rhetorical questions in writing task 2?
No, don't put any type of question in your essays. It isn't considered appropriate academic style.
2. What is the difference between IDP and the British Council?
The IELTS exam is the same wherever you take it. IDP, the British Council and Cambridge University work together to make the test.
3. When describing a map (writing task 1), can we use north, south, east, west even if no compass is shown?
Yes, I often do. I think it's fine to assume that the top of a map is north.
4. The speaking examiner stopped me before I had spoken for 2 minutes. Is that a bad sign?
First, I don't recommend that you time yourself in the exam, so you shouldn't really know how long you spoke for. Examiners sometimes stop candidates when it is clear that the person has nothing left to say. If you spoke for at least one minute and said some good things, don't worry.
5. Is it possible to get band 7 if my essays are unfinished or under length?
It's possible, but not easy. You'll need to get really high scores for vocabulary, grammar and organisation.