I've got Nokia CK-7W installed which is bluetooth if you want it and cradle (inc. charging)if you want it. I always use it on the cradle and it's fine. You can get cradles for most phones, e.g. when I changed from Nokia 6230i to Nokia N9x I got a cradle fitted to match the kit.
You can change volume from the MFSW as well, as all audio is through the "stereo".