I think the TomTom One would suit you. Speed camera locations are available from TomTom, but there is a better source, (I would have to check where), available. Not free, but at reasonable cost.
As far as I know none of the SatNavs have radar detectors.
If you want Traffic updates, this is available from TomTom at extra cost, via your Mobile phone.
If you want an mp3 player, then something like the new TomTom 910 is what you need, (significantly more expensive).