Frenchman St. is where you want to go for live music. There are a ton of clubs in a 2-3 block area. Since you'll be down for Jazzfest, keep an eye out for artists playing shows after hours at these Frenchman St. spots:
The Apple Barrel
Snug Harbor
Blue Nile
DBA
The Spotted Cat
Many folks I know down there make sure that they take visitors to Cochon, best authentic Cajun food in town.
http://www.cochonrestaurant.com/
Another local hangout is Lucy's. It's Drew Brees' tavern of choice and just an all around cool spot.
http://www.lucysretiredsurfers.com/
Mid-City Rock n Bowl is a lot of fun, bowling while being entertained by a live band!
http://www.rockandbowl.com/CalandarP...unths/may.html
The Rebirth Brass Band usually plays Tuesday nights at the Maple Leaf...
http://mapleleafbar.com/
Check out the antique shops on Magazine St., and take a cemetery tour if you're into that as well.
Have fun on Bourbon Street, but make sure you go to some of the great "out of the way" places as well, it will make your trip much more enjoyable.
Oh, and the food is good pretty much anywhere, just stay away from the chains. Make sure to enjoy one of the drive-thru daiquiri shops as well!