What is your car? and which year is it? if it is mk5 buttons will not work. With CH steering wheel controller maybe volume only buttons would work, but without it - no, for sure. 315 doesnt support mk5 chasis cars, only mk6.
USB - have you got MDI on your car? two usb seems aftermarket thing.
VCDS - if your gateway is old, it doesnt see the new radio for sure, we've tried it. Also, have you marked navigation on the gateway installation list? From the bad point, could be broken cans part on the radio or faulty wiring.