As he interviewed friends including Eminem, Kanye West and Snoop Dogg for his documentary “Something from Nothing” (opening Friday), Ice-T gave himself some rules. “I didn’t ask questions about the money, the girls or the cars,” the “Law & Order: SVU” star says. “This was about the music. We live in such a gossip-based culture. Why talk to Derek Jeter about who he’s sleeping with rather than how he’s playing?”