On our series (series 7) recorded Mar - Jul 2012, there were 3 shows a day. 1st at about 2.30, 2nd about 4.00, then they change the audience and do the last show about 7.00 (which means you only see one show if you are in the second audience). However, they intersperse the 'ordinary' shows with 'celebrity' ones, and the celebrity ones are always done in the evening, so you would see one show with famous (?) people.
As far as I could tell, the banter was off the cuff, but I could be wrong. Zander certainly has no notes, Richard has some (mostly about the answers) as his laptop is a prop and doesn't work! Some bits were cut out, normally when things get repeated. One odd thing was if Zander or Richard were doing a 'piece to camera' and they stumbled over a word or something, rather than saying cut or whatever, they would just carry straight on and it would get edited. So if Richard was going to say "The answer to number three is 14", it might come out like " Answer to 14 the answer to three the answer to number 3 is 15 the answer to number 3 is 14", which was abit odd when you first saw it.