Yes it does. My car has both a USB and Aux interface and I was able to use the USB feature with it. The one item I noticed is when I used the USB interface my car controlled the music and I could not adjust it on the handset; however, when I used the Auxport I controlled the music on my handset. That may be normal I don't know since this is the first time I have ever had one that worked with the USB.
I would assume yes, as the storage is treated like a portable hard drive when plugged into a PC...I think it depends on how your stereo accesses the media. Not sure how systems like Sync, FUSE, MusicLink, or aftermarket systems access music off of portable devices...just tried it on my wife's aftermarket JVC stereo and I could manage to get it working. Good luck!
I have 2011 Honda Civic, which has an option to connect an iPhone using USB to play songs, when I connect my Lumia 920 to it I get an error message saying this device is not supported, I don't know if Lumia 920 is not supported or Honda Civic doesn't recognise Lumia 920, hope this helps.