I'm totally with you, I need to understand what I'm getting into before I'm in it or I have a bit of a freak-out, even at age 36.
Granted, the questions might be "kid stuff", but one must remember the point of the test itself. If they're trying to ascertain if you're able to do "simple thought skills" then this "kid stuff" is apropos.
As for skewing the results by practicing - not really. The questions on the website aren't actual test questions, they're just LIKE them so one knows what to expect. If you want to really dig into the "doesn't practicing skew the results" please see the MENSA website which encourages potential members to take practice tests before doing a real (proctored) one. Heisenberg uncertainty principle applies, granted, however we're not seeing if a cat is dead or alive, we're just taking it's temperature.