Regarding "study" for the aptitude test, a couple of random musings.
You may be able to practice specific examples, even learn some types of tests, but does this make you more "apt"?
This test of "aptness" is a measure of your suitability for the companies purposes,can you learn suitability?
If they find "too many" people are appearing suitable via the test, then surely they will alter the test to produce the result they're after.
Can all the study in the world increase your IQ?
Dunno.