Right.
1) It is the APAT main event so you are playing for money, winner gets about 3.5k(I think) on average depending on runners but there is also the added incentive of a seat in a GUKPT event to the winner.
2) Once you have paid you have a seat
3+4) I have played about seven apat events they are good fun, good value and a ideal place to start your live poker experience.
5) you do not have to be with blue square. You may find that all seats have been taken for the luton event though.