FIRST AND MOST IMPORTANT: IF ANY OF THE CANS ARE BULGING, THROW THEM OUT IMMEDIATELY!!!!! THAT MEANS THEY ARE SERIOUSLY SPOILED AND COULD KILL YOU. 
Don't even open them -- just put them right into the trash. Also, if a can is leaking, throw it out; if the food inside can get out of the can, then bad stuff can get in.
On some packaged foods, the date really, REALLY matters -- such as anything fresh like dairy or bagged salads or meats. After the printed date (and sometimes even before, if the food hasn't been stored properly in its travels from creation to you

) the food will most likely be spoiled and definitely should be discarded.
But the date on most canned goods is (at least to me) an indication less of whether the food is good in the sense of "not spoiled" and more in the sense that the flavor and appearance will not be as good as when it was first canned. I have kept cans of cranberry sauce for years

after their date, and they were just fine. Gravy, broths, and so on can probably also stay on the shelf a long, long time after the date and still be edible. Not as good to eat as earlier, but still edible.
That said: if the stuff in the can has a lot of acid in it (such as tomatoes), you don't want to use it if the date is a long time ago. This is because the acid in the food will eventually eat through the can lining and cause damage. And, as I said above, if the can is damaged -- leaking, rusty, or deeply dented -- you don't want to take a chance that the food inside is still good.
Hope this helps! (and glad you find the site useful!!)