- This doesn't sound like the expected behavior - and certainly worth a phone call or a check with the local Service Center.
- Nav voice is controlled from the center console touchscreen. When the navigation system is in a route, you can change the volume by pressing on the top of the navigation turn list window - and either mute/unmute - or change the volume. If you can barely hear it, there could be a problem with one of the speakers (possibly the driver side speaker). With ours, setting the volume to 3 or 4 is usually more than enough to hear the nav voice. Plus, the music should be muted while the navigation voice is playing so even if the music is loud, it shouldn't matter.
- The "free" slacker gives you songs similar to your criteria, but not necessarily a specific song. You should be able to pay for a premium subscription, that will give you more control.
- More details are needed on this one. If you're trying to sync music using the USB cable - that isn't supported. For a USB connection, the car is only providing power to the phone - it isn't accessing the files stored on the phone. Instead, you need to set up a Bluetooth connection to your phone (which is also needed to place calls on the phone, or access your contacts and calendar). Once the BT connection has been made, then you must run a music app on your phone - which will play audio over the car speakers, when you've selected the phone as the media player input source. Of course, other cars have better smartphone integration - and Musk has previously indicated an intent to have some form of "screen mirroring" at some point - but we don't have it today.
While the above items are annoying, they shouldn't be showstoppers - and it would be difficult to build a case that the above issues, even when combined are sufficient to justify returning the car for a refund.
You might have a stronger case on items such as automatic wipers (promised, not available, and currently no promise of if/when we'll ever see that with AP 2.0 cars), AutoPilot 2 operating at AP1 levels (promised for December 2017, still not there yet, though getting closer), XM radio (missing station list, no category list, difficult to switch stations without the station slider removed in the 8.0 release a year ago), ... Though, it's likely Tesla will address these with software updates, so it would likely be difficult to make a case for returning the car.
OP, do you have any other concerns?