This happened right in my back yard. I don't personally know Jerry Hall but I have a couple of friends on his support team and our dive shop loaned tanks and other things. I know he raised some money for Speedway Children's Charities doing this. What I was told is that yes he wore a full face mask and also wore double wetsuits...I believe 5 mil. He purged really well before going into the water and basically ate astronaut food. He also had a tv, speakers, as well as an underwater toilet down there. The biggest part for the support team was keeping his skin intact. They had to put some kind of a cream in his gloves and boots. They stayed with him 24/7 and played board games and just anything he wanted to do. As far as surfacing, I was told that they surfaced him at one foot per hour and I am unsure of if they did O2 or not. The dive was done at 15 ft. There was a huge after party on Aug 3rd at the marina where he set the record which also raised money for the Speedway Charities. I saw him then and he was just covered in sores from where his skin degenerated. I heard he immediately went on antibiotics. Definitely not a record that I would want to hold but it did help a noble cause.
One really cool side note: While he was doing this, his fiance took lessons and became OW certified and dove down to see him. I hear they are married now.