nuoyg, has made a good point that you are in a way interviewing them as well, and if they have asked you back,they must have liked what you said at first interview, as for references, ask them what they want ,quite often somebody that knows you well as a person outside of work will do,long as it is not family, you must just relax, sounds to me like they have a job for you, just be yourself and all will be well, good luck with it,
Thank you society, not so sure about that myself, i can only say what i would do, and hope it helps, but that was a nice thing to say, cheers