Re: Could I catch the flu from this???
I'm not sure of the specifics, but viruses require certain conditions to stay alive, depending on the virus. Maybe someone else here knows the specifics, but my understanding is that a virus cannot survive for very long away from a human host. I know you can spread germs on surfaces, but I don't think they can live for more than a few hours without a human host or appropriate conditions.
If your food package was mailed to you, it is unlikely that a virus would survive the transport before reaching you.
This of course is quite different from the situation of a bathroom door handle where a virus germ can be transfered in a matter of minutes to many hands passing through.