I'll answer these questions one by one.
I attended Beat the Clock, Press Your Luck, and Family Feud. The sets were AMAZINGLY authentic. There were of course a few very small changes made to each set, to accommodate new technology. They were even to scale with the originals. I won't say which of the three was most impressive; that'd be a spoiler.
Ricki was everything you wanted in a host. Nice, very friendly, generally acommodating. Man she had some rapport w/ that audience. I didn't even know who she was. People were going "We love you Ricki!"
These shows were taped in 46, the studio *next* to American Idol. Rich Fields actually did warmup for our audience and he noted that AI was in the studio next door.
The final question is hard to answer. There weren't a lot of actual ticket holders at these events. It's such a new thing, and really so few of us even know about it. "Seat Filler" groups accounted for most of our audience at each show.
I will say that as each taping went on, word of mouth apparently spread! The first taping I went to had maybe a dozen or so ticket holders, but by the time I witnessed the last taping of the series, there were in excess of 100 people waiting in line for an hour!
and do bear in mind, 36 and 46 are HUGE studios! We're talking stadium seating here folks.