Goose fat or duck fat are common fats in French cooking .... like bacon drippin's are in the Southern part of the US ... and smaltz (chicken fat) is used in Jewish communities in New York and elseware. It is both a fat for lubricating the pan to cook things in as well as a flavoring.
If it's in a can that has been sitting in the cabinet for a year ... you might want to taste it to make sure it has not gone rancid. Fats - animal, vegetable, or nut go rancid ... usually in about a year. But, if it is in a sealed can ... that might prolong it since air didn't get to it. If it doesn't taste rancid ... stick it in the freezer!!! That will extend it's life 2-3 years.
As for uses .... just think of where you would use any other fat or oil ... and think about the flavor it would add to the dish. Sweetbreads and onions sauted in goose fat would be yummy ... chicken sauted or fried in goose fat would be, too. Saute some beef cubes, onions, and mushrooms to make a beef stew ....
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain