DCFS in some states is Department of Child & Family Services; the government has intervened in their family situation. Kanye is talking about the underprivileged status of many children who are "in the system" or diagnosed with learning disabilities.
Snoop is inviting another rapper (Kid Cudi) to start rapping on his track. He is affectionately referring to him as family (common for "Uncle Snoopy") and "blaze that shit" is slang for lighting marijuana.