but for FM I have to turn the volume up over 0 dB to hear it, and the quality is not good.

Your car's antenna amplifier is not connected properly and is not getting powered up. See the troubleshooting section of the FAQ at riocar.org.

I get a horizontal line across the top of the screen,

Known bug, fixed in the next (2.0b3) release.

Note that 2.0b3 is still in beta and it has its own set of bugs, use it at your own risk.