What are Bluetooth/wireless headphones like with Nexus 4s?

M'kay, so I didn't manage to get a Nexus 4, but I will be when they're finally back in stock.

-What are Nexus 4s (or previous Nexi/other Androids if you don't know) like with regard to Bluetooth/wireless headphones?

-Are headphones that are advertised as "wireless" necessarily Bluetooth or do they sometimes work some other way?

-I have just broken the wires (kittens, hrmph) of some Sennheiser HD202s - will I be able to get wireless headphones of a similar quality for my price range (think the Sennheisers were £50-60)?

Would anyone recommend any particular headphones (pretty cheap, say under £70, I don't want to stretch much and even then not unless it's really worth it.

Thanks for the help in advance :D