rachel mcadams is polaris, seen her in mean girls, sherlock holmes and the wedding crashers.
ryan phillipe is havok, seen him in cruel intentions and crash, and he used to be married to reese witherspoon
lawrence fishburne is bishop, seen him in matrix movies (morpheus), he was the voice for the Silver Sufer in the FF movie and he's staring in CSI.
I've seen the actress for Emma b4, but can't remember where.
Gambit may or may not be Taylor Kitsch, can't tell cause of all the photoshop.
No idea who Psylocke is though.