Its been awhile since I went to fanfest, so maybe someone else can chime in if there have been changes recently. In the past, there would be a stage where one to two players would sign for about an hour or so. It is not announced ahead of time who is signing at what time. When you get through the line and get your autograph, you get back to the end of the line. Most of the days I was able to get all of the people signing, but if the lines are long and there are a lot of people, you may not be able to get all of the players. It is strictly one autograph per person.
Depending on how strict the volunteers there were watching the lines, there was a lot of cutting in line, especially when a "good" player came out to sign.
During the second day I was there, someone got the lineup and times somehow. I don't know if someone talked to security or not, but that information made its way around the people waiting in line. The list wasn't completely accurate though.
In the past, ESPN did a live radio show during the fanfest, and different players would go through and interview. This info is usually posted on the fanfest website.