[LAU] convert 24 bit flac files to 16?

I'm sure this is an easy one but I thought I'd ask here first..... I've got a bunch of 24 bit flac files that I'd like to convert to 16 bit in order to play them on my Android phone. I'm not totally sure how they've been encoded to 24 bit (I must've done that at some point but I don't remember when/how). Also, I've noticed that a bunch of them are also "multi-channeled". How in the world did they get that way? I've never recorded anything but to 2 channels so the fact that I have a few flac files that have "8 channels" seems really weird. So, really, I'd like to be able to knock down the bit rate from 24 to 16 and also put these into stereo as well. Command line and/or gui is fine. Any input is much appreciated. Thanks. -Aaron