Be careful heat can cause damage to the battery. More heat = less battery life. That is why my iPod charge lasts almost 2x that of my husbands he leaves his in the car and mine is usually in my purse.I love how seamless connecting the iPod is to the stereo. I love it so much, actually, that I keep my old iPod in the car all the time as my permanent jukebox. The summer heat doesn't seem to affect it in the glovebox.
The USb should would with any device that has a uSB cable or connection. I am using a 16GB USB drive in mine and it has no problems with that. I also use a iPod in my wifes Focus and it always stays in the car and isn't used for anything else. Some people are actually using external hard drives and mounting them somewhere hidden in the car and plugging it into the USB2 on the APIM (audio protocal interface module). This was discussed on another thread in the ICE section if you are interested in that. I have found though that on my wifes Focus that if you have more than 10000 songs then you lose the ability to say "play track" but you still can say "play artist","play artist","play album","play genre" .So if they ability to chose a specific song isn't important to you then you can have as many songs as your storage device can handle. At least I have not found the limit where you lose the other commands and I have over 32000 songs on my iPod.Didn't realize that the USB would only run an iPod.