The interview is a two-way process. The company interviewing you will want to find out whether you are suitable for the position and you will want to find out if the company and position are right for you. You should therefore ensure that you have enough information to make up your mind whether you want the job. For example:

What will be my responsibilities? Where will I fit into the overall organisational structure? Who will I report to? Where does he/she fit in the structure? Who will report to me? How experienced are they? What do you expect me to do in the first 6 months? What level of performance do you expect from me? Who are your customers? Where is the company going? Upwards1? Expansion plans? What are the chances of advancement/promotion in this position? When? What will be my salary, benefits and bonuses? Will travelling be required in this position? Will relocation be required now or in the future? What training do you provide? When will you decide on the appointment? What is the next step?