I live in Columbus. If you want lunch, stand with your back to the Convention Center, cross High St. and walk for half a block. Behind the buildings you'll find
http://www.northmarket.com/, which is a nice place to grab some food. If you want some place to go after the con the North Market is near the Arena District and German Village, which are both nice. I'll stop by during the con (how do I sign up to work the booth?) and give more concrete directions. It'll be a shame to drink y'all under the table, but I guess it has to be done.
Tom