taking it a sentence at a time:
I probably took more than anybody could survive.
-> I did so many drugs I should have died [from an overdose].
I was banging 7 gram rocks
-> I was taking 7 grams of hard drugs [crack cocaine, probably] at a time.
That's how I roll.
-> That's the way I am.
I have one speed. I have one gear: Go.
-> I take chances, I take risks, I don't care about the negatives.