Nuthin' But A G Thang

The Chronic Dr. Dre
Dre is about to sing his verse; he is being called to the mic. Creeping is also driving and a phantom is a type of rolls-royce, so his flow or style of rap is smooth like a ride in an quality vehicle. "approach in a smooth, ghostlike manner"
Gotta break 'em off somethin' means to share the wealth or to give something meaningful to someone else. In the context of this particular part of the song, it means a very good song with a strong beat.
The Notorious D.I.P.
You're acceptable enough to me to get a good chunk or piece of the weed.
With all due respect, 'clockin a grip' doesn't have anything to do with guns. 'A grip' is slang for 'a lot.' So, what he's saying here is that he's making (clockin') a lot of money as a pimp. The Dolemite bit is pretty spot on though.
Fading means falling down in the top music charts until you're no longer signed for more records.
boxer Evander Holyfield's nickname was "Real Deal Holyfield"...he is saying that he is even realer (more honest and tells it how it is) than that
good weed has a very distinct almost stinky smell. so, he is saying he broke off a piece of good quality marijuana to get ready to smoke
when you're driving putting one hand on the steering wheel and leaning either towards the passenger seat or out the window, all the while bumping to the beat. probably smoking a blunt
Any obstacle or item, setback or adversity is inconsequential when you have this mentality. "A G Thang" just means "A gangsta thing," a relaxed, swagger mindframe.