The only advice I can give for the interview is to learn about all of EUrocontrols different sites locations, a brief overview of what they do at each site and and what it is called
e.g IANS Institue of air Navigation Services - Luxembourg _ Provides traning for ATCO's.
If you learn all of those you will kinda of impress them when they ask what do you know about eurocontrol etc. Learn what the Upper area controller does, COnroling above 24500 feet etc.
They will ask a lot about yourself and test weather or not you feel you are upto the job etc and they will also ask a bit about the group work tests you did how the ywent why they went wrong etc! They will also throw in a few maths problems just to pressure you a bit more. Just Relax!!
IT is supposed to last around 90 minutes. I was finished after 45 and had the Panellaughing with me, really didn't think I had passed but I did and I start training in 3 weeks time! Good Luck!