Some of the details in these tips are really interesting, I loved reading them (i.e. really thinking about our craving vs. stuffing our faces until we find it). I agree with some comments that were made concerning studies vs. "real life." What we have to remember is that scientific research studies are conducted in very rigorous ways, trying to remove as many variables as possible and limiting the effects of 'external' factors.
Sooo many things can make these tips true or false for different people: not being in a research study (hurray placebo effect!), environmental stressors, genetics, history of dieting (too much dieting apparently slows down your metabolism), neurotransmitters (lack of serotonin, often associated with depression, can make some people feel more hungry)...
As far as diet soda is concerned, I have heard that when you ingest sugar substitutes such as aspartame, your body is expecting to receive sugar energy, and when it doesn't, you crave sugar. Personally, I find that having a diet soda when I already crave sugar is actually helpful, and I don't crave sugar afterwards. I also have some after what I feel to be a 'normal' portion of food, and it helps me stop eating when I know I should stop but that I keep going anyway... so it helps me not to overeat!
However, for others, tasting something sweet might make them want more sweet, so they reach for sugary foods? Either way, I think it's a trial-and-error thing.