Hello !!
First of all thank you for your answers.
I really don't matter that they change all that story about the house-elves, because it's a little boring, but about the world cup, the obsticles in the maze... I don't know what they changed exactly, but I hope it's not far from the true story...
I read somewhere here as well that at the Yull-ball they exagerated (I don't know if I wrote this right) about Hermione-Ron, and I'm really sorry for that !!