Memorial Day weekend signals the start of summer, and experts are lining up to help people master techniques for barbecuing and grilling outdoor meals. They include two cooking schools and two free hotlines, including one geared to make digital natives happy by answering questions not just by phone but via social media and texting. Southern barbecue is rooted in four regional styles — Texas, Memphis, the Carolinas and Kansas City — and the Cook Street School of Culinary Arts is offering a class for home cooks on Kansas City barbecue as part of its series on American Regional Cooking. Kansas City barbecue was made famous by places such as Arthur Byant’s, where the slow-smoked ribs inspired writer Calvin Trillin to rhapsodize that it was possibly the best restaurant in the world. Cook Street’s class will emphasize the difference between grilling and barbecue and will drill down on the art of the Kansas City style of slow-smoked meat and tomato and molasses-based sauce.