Prepare charcoal grill for cooking with indirect heat. Center drip pan in bottom of grill; add 1/2 inch water to pan. Place 25 charcoal briquettes on left side of pan and 25 on right side. Heat 20 to 30 minutes or until coals reach medium-high heat and develop a light coating of gray ash.
Meanwhile, remove and discard neck and giblets from chicken. Rinse chicken with cold water; pat dry. Sprinkle cavity of chicken with salt. Place lemon inside cavity. Fasten neck skin to back with skewer. Turn wings back and tuck tips under shoulder joints. Rub outside surface with oil; sprinkle with paprika. Insert meat thermometer so tip is in thickest part of inside thigh and does not touch bone.
Place chicken, breast side up, on grill rack 4 to 6 inches directly above drip pan. Cover grill; cook 1 to 1 1/2 hours or until thermometer reads 180°F and legs move easily when lifted or twisted. Let stand 5 to 10 minutes before carving. Remove and discard lemon from inside of chicken.