I'm interested in grad school, where do I start?
A quick reading that will help answer many of your questions is Some Important Things Most Students Never Ask About Graduate School by Rob Candler, a Stanford alumnus.
How do admissions work? What degrees are offered?
I'd like to visit, who should I arrange that with?
Start with the Student Services Office and tell them the dates of your visit and who you want to meet. They are extremely helpful and will try to get those faculty on your schedule or their students if that faculty member is not available. By the way, it helps if you give some context of your interest and background, e.g. topics of interest, current year, degree desired, your background.