I had understood that the tradition of pancakes started as a way to use up the eggs and milk in the house before fasting. I can't see reference to that in the entries you point to, but the Wikipedia entry on Lent suggests that this may have been the case, as traditionally people gave up meat, eggs and dairy products. Doughnuts would be another way to use up those foods before the fast.

The connection between Groundhog Day and Candlemas was explained in the New York Times:

In its earliest incarnation, Groundhog Day or something like it was a pagan observance, marking the midpoint between the winter solstice and spring equinox, according to historians.

Burrowing animals like the groundhog were said to have the supernatural ability to foretell an early spring. The observance merged at some point with the Christian holiday of Candlemas, and the tradition embodied in this proverb: "If Candlemas be fair and bright, winter will have another fight. If Candlemas brings cloud and rain, winter won't come again."

They do say that all religious holidays have a pagan origin, don't they? Apologies about the garbled apostrophes/quotation marks etc., we've just updated to the new Movable Type version and are experiencing a few teething problems.