We've talked food more than once... there's even a "Food" thread, which was somewhat adequatley started in The Feast before the Lounge wing of the hotel was built.

Excess carbohidrates will indeed make you fat. The USDA Food Pyramid has been questioned from its emphasis on carbs without distinguishing between good carbs (whole grains, etc.) and starchy/sugar carbs, and from not distinguishing between good (unsaturated) and bad (saturated) fats.
The Scientific American article Rebuilding the Food Puramid from the January 2003 issue should be fully available online and may be interesting for you.
I've also seen questionings about the true effect of total ingested cholesterol in its levels in the blood (most of the cholesterol in your body is actually synthetized, not simply absorbed, by the body to make many essential hormones), the link between ingestion of saturated fats and high cholesterol still holds true AFAIK.

For weight control the formula is simple: burn as many Calories as you ingest, to lose weight burn more Calories than you ingest. The best way to do that? exercise more.
I only preach that, don't practice it (yet?) and I'm slightly overweight.

Did you know that "Calories" in food labels are actually kilocalories?
I swear, if people saw in the labels that they're ingesting 500,000 calories or 500 kcal and not 500 Calories we would be more careful.