Stelar said almost everything..
The money you get back is the amount of the cheapest ticket you can get!! For example, if you chose to fly with KLM for a 1000 euro's, and you can also fly with British airways for 300 euro's, you'll get 300 euro's in return (if i remember correctly)
You also get 10 euro's extra for all the bustickets you need. From trainstation (if you arrive at Maastricht station) to hotel, from hotel to EC and those 2 back.
But indeed.. just bring all the tickets + bank account form and you'll be allright.. Takes about a week or 2 before you get the money from EC..