They've posted certain acts days on twitter.
Friday: Noel, Keane
Saturday: Sugababes (The Streets by process of elimination)
Sunday: Paolo Nutini, The Reytons
Also confirmed Katy B is parklands
The Thursday seems very strong this year.
Paul Heaton & Declan McKenna (who i wouldn't really question if he was Thursday headliner himself) and then The Hunna as well and a couple more.
Not that I'm aware of, just have shared a headliner a few times (Kasabian 23, Stereophonics 22, Libertines 18, Stereophonics 17, Noel G 16)... more a case of gives an indication what acts are headlining this (similairish) size festival next year