Innit and arxed are definitely creole patois. The cockney is ain't it and arst'd. The cockney ain't it is used at either end of sentences as a question: "Ain't it cold aat?" or "It's cold aat, ain't it?". The creole innit is used as punctuation at the end of sentences: "I got a new car, innit." Translated into cockney, that becomes, "I got a new car, didn't I?"
The cockney dialect would have variations, such as didn't it, ain't I. In creole, there is just one innit.