I luckily had the opportunity to be promoted within Express, before my departure from the company, as a interview/screener of applicants.
First of all, it is always better to turn your application in directly to a manager. That way you can put a face to the application they are reviewing. Managers are always looking for energetic, fun, and fashion oriented applicants. They want these individuals to look professional BUT fun and into fashion.
During the interview it is very important to have a personality. You would be surprised how many interviewees come in with lackluster and mundane attitudes and personalities. Express want's associates with drive, ambition, and eagerness. Even if you already have a full-time job and you are just looking for part-time work with great benefits and discounts, Express wants you to at least be someone with ambition and excitement. This really needs to come off in your interview.
Questions are fairly easy one's around "Tell me about yourself", "What do you do for fun", "Why do you like Express", "Why would you be a good fit here", etc. Their pretty much screener questions to see your ambition, interaction, and level of professionalism.
One last important detail. When putting in your availability it is ALWAYS (and this is usually the case with most Express store locations) important that you are available weekends and most weekends. If you currently available weekends and their might be a possibility later that your weekend availability might change, still indicate you're available. Your availability can be changed once you've got the position and explain it with management.