Most car stereos assume the device is a
UMS (Universal Mass Storage) or
MSC (Mass Storage Class) device (same thing different names). WP uses
MTP (Media Transfer Protocol) so unless your stereo has that ability, you aren't going to be able play files from your Windows Phone. Bluetooth, or AUX in is your only way with WP.
As for the charging, again, some stereos just don't provide the power to charge devices. Not much you can do, except use the "cigarette lighter" adapter.