The area around my r 6&7 rib - the costal cartilage feels like friction or something crackling there, is it "normal "?

Cartilage and ribs: The 6-9th ribs share a common cartilagenous connection with the sternum. You may have had a cartilage separation - very painful but usually due to high force trauma. You may also have costochondritis - which is a painful inflammation of that joint. A rib x-ray should be able to give some clues.

No It is not: Costochondritis is the most common cause of chest pain originating in the chest wall. Symptoms include: pain and tenderness in the locations where your ribs attach to your breastbone .Often sharp pain, though also dull and gnawing pain location often on left side of breastbone, but possible on either side of chest , pain when taking deep breaths, pain when coughing, difficulty breathing.