Yeah, I freeze Costco milk all.the.time. "Someone" in our household freaks out at the "expired" milk, so I black out the date with a Sharpie marker. Stupid, but it works.
Also re: freezing cheese. You can do it, but it does tend to make it crumbly. Trick is to grate it first, flash freeze in thin layers on cookie sheets and then dump it onto an airtight container. Seems like a lot of work, but isn't really. Of course, if you score a deal on grated cheese, just toss that sucker in the freezer as is.