Lets first define the role of a FFL. They are primarily to assist and encourage high school students who have a desire to apply to WP. Their experience has a wide spectrum from adult who never went, parents of, to alumni. Their information can be dated but most are current. Do they have influence in the selection process? Maybe, some may sit on NOM boards, others may have a solid relationship with the RC. FFL are not available in all areas of the country and thus an interview is not required from WP. They do have access to a applicants information but at a low level. Its basically indicates the percentage of how much an applicant has completed their file.
Your interview is based on how much information you give them. I would encourage you to start a relationship and visit with them on multiple opportunities during your process. This will be beneficial with question that may arise. They also have the ability to compare you to other students who are also applying from your area. PARENTS: Take a step or two back and allow your DD/DS speak for themselves and learn how to speak with adults. They will not damage their opportunity for admissions. Your FFL does want to know about your DD/DS from first hand not through the parents. I would dress in slacks, nice button shirt and nice shoes. No t-shirts, holes in the knees or dirty sneakers.
Push Hard, Press Forward