The New Orleans Jazz & Heritage Festival is the Big Easy’s annual celebration of its best features: music and food. Whether you head down for the first weekend (April 25 to 27), the second (May 1 to 4), or both, you can catch Kermit Ruffins — a one-man combination of song, food, and good times. For 15 years, Mr. Ruffins and his Barbecue Swingers have performed on Thursday nights at Vaughan’s Lounge, a low-lit dive with sawdusty floors in the section of town called Bywater. There, Mr. Ruffins — a trumpeter and vocalist strongly influenced by Louis Armstrong — plays songs such as “Smokin’ with Some Barbecue,” “Chicken and Dumplings,” “Breakfast, Lunch, and Dinner,” and “Hide the Reefer.”