Pillowcase,
Once you have achieved the minimum education standard I doubt very much that it would affect your application in anyway.
Very briefly in reply to your questions :
1. Not really, I only got a 2.2 in my degree and there are plenty of guys out in NZ with no university qualifications.
2. No, I never held a respected job before CTC.
3. Yes.
4. Not really.
5. No, you will not have to give a presentation during selection.
In summary I wouldn't worry about it. Answer the questions truthfully, and get prepared for stage 2. I would recommend getting a book such as, "How to pass atiptude tests." There is plenty of detail with regard to what to expect during selection on the CTC website and this PPrune thread.
The CTC course is a good laugh, and I've enjoyed it, so stick with application.
Good luck
Timeout