the white 920 is exclusive to joining ee network, and ee only do contracts at the mo, so its exclusive to a ee contract

as for the other colours people have said you are able to buy the phone on pay and go from orange or tmobile for 399, however looking on their websites there is no indication they offer the phone to buy on pay as you go.
as for buying the phone from phones4u, the handsets have been purchased from EE, so they do come with the free earphones
on a separate note, the battery level app for 79p that you say is not updating the live tile, i had a similar problem, but have a look around in the app store, there are many similar battery apps most for free that do the some thing but better. i like the app 'battery meter' cos it gives estimated talk time too.