I wouldn't overstress with regards to the aptitude tests.. most of the trainees I'm spending my time with, just like myself, didn't sepcifically prepare for them. It's something you do with your natural brain resources. The ATC training will improve your ability to process information, the aptitude tests are there to make sure you have a suitable clean sheet on which you can build your training on. I wouldn't dwell on it.
The personality types are also irrelevant I think.. we do all these exciting learning styles questionnaires, to find out we are all different but we can all achieve a common target in different ways.
have fun
Ivor