Just on that line "You're a wonderful Human Being"... In the original scene, remember that Jabba -was- a human being; so originally Han wasn't being sarcastic (well at least not about the "Human Being" part). But I think that GL left it in to be interpreted as sarcasm in the updated scene. I also think that the cringeworthy "Tail treading" bit was only put in because of the way the shot was originally filmed, IE Han walked around behind Jabba. Of course originally he didn't have a tail, but when they were sitting down deciding how it would go, GL must have said"I know! We can make Han step on Jabbas tail"... maybe he thought it would make the whole scenario more real/convincing? :-P