I already said the Crusader was an improvement over the Paladin but that it was not a good allocation of resources since the battlefield is changing.
Work on your reading comprehension.
As for SecDef's needing prior experience dealing with how the DoD works, many civilians do have that experience. Many SecDef's do have prior military experience including Rumsfeld. He was a Navy pilot. But it is not necessary. A congressman who has been on the Armed Services Committee or the National Security and Military Committee qualifies.
The military should always be under civilian control. Truman had it right, you have it wrong.