The actual practice portion usually lasts 90 mins or so, just depends on what day you go.
There will be positional groups all over the practice fields at first, working on individual drills. Eventually, the offense and defense will get together for 7-on-7's and eventually scrimmage scenarios as camp progresses.
Last year, I was right next to the linebackers and secondary doing individual drills...which was really cool. The practice went to - they had the QBs and WRs on the second field furthest away from the berm where you stand, so it was harder to see what was going on over there (probably by design).
Pete has music blaring during the drill sessions and it's pretty high tempo and energetic.
Although they are not "required" to, quite a few players will come by after practice and sign autographs down the receiving line. Pete usually spends a lot of time doing that as well. John Schneider walked up and down the line during the practice I attended, and I got to grab him and chat him up for awhile which was great. Just remember, with less available camp time now they are on a tight schedule and usually have meetings or lifting within 10-15 mins after practice.
A lot of the players will interact with you during the practice, at least acknowledging yells and such lol.