Will have to research the audio aspect as I funnel all audio through system audio rather than HDMI.
Do you need twinview? Did you install the proprietary driver? If so, does your card support simply bridging your Desktop from one display to the next without twinview? This would be simpler, which is always better.
By trimming screen, I take it that you mean the edges of your desktop are not visible due to TV overscan? If so, then the solution is to turn off overscan on your TV. Most TVs will have a setting to do this, but it is called different things by each manufacturer. On my Sharp it's called "dot-for-dot". On others it may be called "computer mode" or similar. You will have to read your TV docs to see.
If this doesn't work, you can install the proprietary driver and use nvidia's overscan compensation mode in the N-Vidia Settings Manager app. Some drivers will have this option, some won't depending on your card and the driver you installed. If no such option, you can also try:
which might allow you to set overscan on (I've never used it, so you will have to go through the man page, learn and configure it yourself).
sudo apt-get install nvtv