Ahhhh I thought that 22th meant the last one. Thanks. How have you been, Rach?

The fact that Walt might be "special" was something that bothered Michael even before the crash, we know this from the flashbacks. I believe it was Walt's mother who told him so...or was it the step father? Yes I think he learnt it in Australia.

So if the island is a representation of what goes in the characters' mind (fears, hopes, obsessions, addicttions), the thing about Walt being tested makes sense.