A Calico is a type of machine gun. My Calico is loaded and ready with additional clips of amunition available.
the sound system in his car is turned up to the point that you can hear the music he's playing at least one street away
Diamonds are often referred to as "ice" because of their clear, glassy nature and resemblance to ice. His chain (necklace) has so much "ice" in it it's making his neck cold, allegorically speaking.
Refers to the song "Let Me Ride" from Dr. Dre's debut solo album, The Chronic, in which a young Snoop Dogg makes an appearance