The first one, when the producers expected way too much. It was just too hard to take in, though all the mishaps were rather comical.
It's so true, but the crew deserved a bad episode for not shooting a pilot of any form prior to the first episode.
At the very least, they could have tested it. Actually, there was a Kirk Fogg interview in which he said he tested the temple once before every season.
Actually, if I recall, he also said that he didn't have to deal with guards.
Kirk, while he said he didn't, had a better grasp on the objective than the kids did (not to mention the strength to get him to the artifact and out), so it's not a perfect comparison, but I can see your point. (I wonder if Dee Baker got to run through it as well?)
If Kirk did, Dee might have, but I wouldn't bet on it. And yeah, Kirk had an exponentially greater idea of what he had to do. But, I suppose if the kids had paid attention, run through it verbally and in their heads, they could have done as well as Kirk.
And as a little bonus, they also had Kirk's infinite wisdom. "The door's unlocked!" and stuff like that.
EDIT: Kirk may have been physically stronger, but that doesn't mean he had better cardiovascular fitness. He hosted a game show, probably worked out occasionally, but most of the kids claimed roots in sports, which would require periodic workouts and practices.
That said, it's possible some of the kids had deeper gas tanks, if you will.