The Voices will certainly visit with you and pose for photos, but I don't know I've ever seen them sign autographs - honestly, I suspect they're all too modest to think anyone would actually want their autograph!
About 15 years ago they stopped wearing name tags on stage because there were security concerns, but they've never been shy about telling their names in conversation. There are so many active members that it might be tough to find an accurate list of names. (I've known many of them for years but have no idea what some of their last names are unless we've connected on FB.)