Congrats on your new MS!
I also use an iPhone, but as it is, MS Media Player does not utilize audio sources via USB. Period. There is no hardwired external audio connectivity in MS. If you plug your Droid in, just like with an iPhone, it will charge, but that's it via the USB connection.
As RAW84 suggests, your only options are Bluetooth or USB. If you use the latter, there are a number of other threads discussing the limitations (there are several)... but to your questions, yes, scanning will take place every time you insert the USB stick and the time it takes varies of course based on the number of tracks involved. It's "a couple minutes" if I put in a stick with just a few tracks or podcasts, but OTOH I maintain more than 16K tracks on my primary 256GB USB stick as a subset of my iTunes Library, and it takes a VERY long time to scan -- I put the stick in, cause scanning to take place, then walk away and it's done next time I come back to my MS. I know it won't complete in 20 mins (that's the max I've ever watched it), so takes something longer than that -- IDK how long in reality. I've just learned to compromise and don't update my music very often in my MS like I used to when I had physical hardwired iPod capability in my previous rides. Check those other threads for hints/tips and limitations with USB and Media Player, but two immediate thoughts:
- When you insert a new USB device, Media Player will not always automatically start scanning it (that's a bug IMHO). To be sure it will, go to the Media Player, find the USB port you plugged your flash device into, and select it. You'll see a message that scanning has begun or will begin after the other port is completed.
- Also, if you are listening to USB music and leave your MS, you may encounter phantom playing while MS is off -- again, see other threads for details -- but the workaround is to remember to switch to say an FM channel every time you exit MS, then reselect your USB music again when you get back in.
Sorry, MS is a great vehicle, but there are lots of Media Player issues that have existed for a very long time -- and it's really frustrating to yours truly, amongst others.
My suggestion as it sounds like you change audio tracks often, like what RAW84 suggests, is to use Bluetooth. You'll perhaps loose a little audio quality depending on how you were going to record your tracks to USB because of Bluetooth audio compression, but you won't have the scanning delay each time you change your music or the possible phantom playing problem -- AND -- when you get out of your MS, you'll be able to continue listening to your tunes where you left off and vice-versa.
Enjoy that new MS!