Does cac result of 0 and cimt result of no plaque or 0% means there are no detectable soft and hard(calcium)plaques in carotid and coronary arteries?

No! Atherosclerosis: typically starts childhood, progresses over decades, is only in wall of arteries, walls thicken & arteries enlarge (compensating) with Zero narrowing of opening. While microscopic Ca detectable 10 ys/old under microscope, typically too small to see by usual methods till many decades later. Healthy carotid wall thickness 0.06 cm. Max. without plaque ~0.08 cm. Different arteries usually different.