Does doubt regarding not performing ghusl necessitate redoing it, and how can one ascertain the number of times ghusl was not performed, and is one held accountable for doubt and lack of certainty concerning ghusl, and must one repeat prayers that did not deter from indecency and wrongdoing?

Your prayers are valid, and you are not required to repeat them, because doubt after finishing an act of worship does not affect its validity. As long as you performed the prayer, fulfilling its conditions and pillars, its validity is not affected by it not having restrained you from disobedience.