That violin like sound is a common guitar trick played using the guitar. The volume knob is kept to zero and you pluck the string, so that the attact is not heard and then you slowly increase the volume. For best results you should make sure that the volume POT in the guitar is logrithmic or audio taper. With linear POTs it doesn't come out very well. Try it with nice overdrive and it will sound even better. Another option is to use a Volume Pedal which has logrithmic POT or the audio taper ones and use this before the overdrive. Using it after the overdrive doesn't give a great effect. I usually do this thing with the volume pedal. Check out some Live solos of Steve Morse. He has perfected this.
Palm Muting means muffling the strings with your palm at the bridge or near the bridge of your guitar. You could mute it soft or hard and it depends on what sound you want. With very high gain, and heavy muting and palm at slightly before the bridge will give you a good chug for the Rhythm. Slightly muffling at the bridge will give you a good palm mute for soloing. The police song you talked about has a very soft palm mute. Andy Summers is playing that with very mild overdrive, so a heavy palm mute will make the string sound dead. So for that kind of thing muffle slightly over the bridge and play with a mild overdrive.
I'm the one that has to die when it's time for me to die, so let me live my life, the way I want to. - Hendrix
If you can remember the '60s, then you weren't there. - Unknown
I'm shopping around for something to do that no one will like. - Jerry Garcia
Don't compromise yourself. You are all you've got. - Janis Joplin
On stage I make love to twenty five thousand people; and then I go home alone. - Janis Joplin