I am thinking about addind twitter to our options of advertising. If anyone uses this how does it work. My idea was to ask easy questions about our food and our town and give away food as a prize. When doing this on twitter are thie winners the first to respond via twitter or the first to call the store/ come into the store? Not sure which way is easier/better. thanks

Running contests on twitter is a great way to engage people. If you are running a twitter contest it should live on twitter (have the winner be the first to tweet the right answer) rather than call or arrive on site. Rather have them respond on twitter, then have them come into the store to claim their prize.
If you are running another promotion, contest or something like that, you can use twitter to promote those too.