JayB,
Competency questions are as you describe.
CTC could ask you lots of other questions. There's a lot of information about all of this in the old and current CTC Cadet thread. If you want in, read from start to finish, bookmarking the valuable pages. You won't go wrong, and it'll save you posting questions already posed. Sure, there's loads of pages, but that's better than few. Everything anyone needs is already on the glorious Pprune.
In a nutshell, if you are prepared for any graduate recruitment level assessment process, you will be prepared for CTC, provided that you are suitably genned up on aviation to a level appropriate to your flight experience i.e. no flight experience = reading industry publications, maybe some trial flights, maybe talking to pilots, know CTC and stuff about its partner airlines, typical pilot routine blah blah blah; some flight experience = expect some more technical questions appropriate to your level (from what I gather on here and having talked to people in selection).
Why not apply for some other grad jobs to brush up in preparation?
If time is on your side i.e. you're not old, my advice would be don't rush it. Get a plan together to maximise your success at the first go. You can fail at any time, and the maths test is the only thing you can try again. Some people get told they can re-apply for stage 3 in 6 months time due to some experiential shortcoming, but if you use your time wisely before you apply there's no reason why you can't get through without any of that. And stage 4 is still a pass/fail, even if the odds are in your favour. Plus, if you can demonstrate long term focus, that's another string to your bowand answering questions like "so what have you done to pursue your dream?", willl be a piece of cake.
Best of luck.