Yeah, sometimes a comment or critique will make your energy level take a nose dive. I find it hard, especially during a rush at crunch time, to take any crits because I get emotionally attached to the shot I'm working on. When you invest a lot of time and energy in to something it's really hard if that just get's torn apart. But... that is something we just have to face regularly, so brush yourself down, and get back on with it. Most of the time I'll take a little step back, try and detach myself from it, and then realise that the comment was a good one and will actually help the shot a lot. So keep your spirits up!
On to the next one... wow, that's a tough little audio clip. Laughter is really hard to get right and the way the line is delivered seems much more like a statement than a question. Another challenge here is that the beats are kinda hard to identify. For me it's almost a single beat since there's no real change or shift in attitude from the laughter all the way down to 'Think'. I'd maybe concentrate on one strong pose and just work a couple of gestures out of that.
Re. props and such... What makes this clip hard is that it really feels like we're coming right into the middle of a conversation - that the audio is not isolated. That's not necessarily a problem if you can stage the shot in the right way and put the character into an instantly readable situation. I wouldn't go too extreme on a set or props but try to make the situation believable. I like the idea that he's covering up an embarrassing moment with a little laugh, but I would be careful about adding too much complexity. You said doing it this way means more beats and such but I don't think that's necessarily true. He could be a salesman, a business man revealing the sales chart, a teacher, a magician... perhaps he's just revealed something that is obviously a FAIL and has just read the audience's reaction and it is at that moment your animation begins.