What to expect from 2nd round interview?

I got a 2nd round interview this week on Thursday and I am a little nervous about what to expect.

The first round went well but had some iffy moments too. I asked very good questions and I explained my background very well and my motivations. As its a sales job for an economic consulting firm, they asked largely fit questions. One I tripped on a little was how I would provide our research to a skeptical hedge fund manager or trader. How would I overcome his objections? What would you guys have said?

Back the 2nd interview, what shall I expect? Its with one of the directors and the head of sales for the whole company. Really nervous!! Desperately need this to go well as I need this job. I think as a woman I may have an advantage as its a sales position but still any help would be greatly appreciated.

Any suggestions on what to prepare, questions to ask (I asked the last time about what traits good sales people have at the company, what am in line to achieve within a year and whether they had any doubts about my ability to do the job; they were impressed!) and stuff to do. Again much appreciated.

Thanks!