Cathy,
The spices (which you didn't ask about) you can pitch. :)
For the future: you can freeze spices to keep their full strength and flavor. You have to do it in a very WELL-sealed container. My sister-in-law uses old baby food jars because they seal very well, but if you're clumsy like me at times, this is not a good option. Glass in a freezer is like glass in a bathroom. Not fun.
Baking supplies - well, you might donate the flour to friends who do bake, or take up baking yourself. A loaf of bread here and there might stretch your grocery bill a bit further, and you can try tasty new things (like your cranberry loaf :)
Flour will keep on the shelf most of a year; sealed carefully, maybe longer. You can freeze it (in a well-sealed container) longer, but I'm not sure by how much.
Baking soda/baking powder, as long as they are again, well-sealed, will keep indefinitely, but go by the date on the bottom of the can. (if it doesn't have one, well, go by the date you bought it and add a year if you trust the store).
Oil you will know if it goes bad - it smells funny - it's called being rancid. Kinda smells like dust got mixed in, but it's still clear and all. You'll just have to keep tabs on it, is all. It comes in its own container, and while I haven't heard of freezing oil, I wouldn't either, but that's a personal choice.
If you need new spices, there is a place on Jefferson Rd/Mushroom Blvd in Henrietta. Tadco. Beware, they sell in bulk as well as small amounts. :)
Good luck,
M.