Lets face it most of the top Nazis were idiots, thank goodness, there was an allied plot to kill Hitler, but he was doing so much harm to the German war effort with his stupid orders and ideas ( he thought he was a military genius, he wasn't ) that they finally decided to let him live as he was doing far more harm alive than would possible be inflicted if he was killed.
A lot of Goering's judgement was probably effected by his morphine habit which he picked up I think after being injured in a car accident in the 1920s.
The Spitfire was a great plane and constantly evolving, there were over twenty-four marks, I think the clipped wing version was for ground attack, there was also an extended wing version with a pressurised cabin for high altitude work and in some the Rolls-Royce Merlin engine was replaced by the more powerful Rolls-Royce Griffin engine, these were used to chase down V1 pulse jet powered flying bombs, and don't forget the lady engineer who solved the Merlins problem of cutting out during negative gee maneuvers because it had a float carburetor instead of direct fuel injection which the Me109s had.
As planes go it was excellent for photo reconnaissance ( one photo recon pilot based in Malta flew so low over an enemy harbour that when he got back the ground crew found a ships ariel wire wrapped around his tail wheel ) plus don't forget the Seafire, a carrier based version the Royal Navy Fleet Air Arm used with great success, but to be honest the bulk of the work carried out in the Battle of Britain was by the Hurricane, three out of five enemy planes shot down were by Hurricanes if I remember rightly, who had the very important job of going after the bombers ( Do17s, He111s and Ju88s ) while the Spitfires engaged the escort fighters ( Me109s and Me110s ), if we could have won without the Spitfire is very debatable but it sure as hell helped having it at the time, and don't forget Spitfire snobbery, a lot of german pilots swore blind that they were shot down by a Spitfire when there weren't any about for miles.
Goering once asked german ace Adolf Galland if there was anything he wanted, to which he very cheekily replied that he would like to have a squadron of Spitfires please.
The Battle of Britain is really a vast subject with many, many aspects ( radar, observer corps, Bletchly Park, our command and control systems compared to the German night fighter command system ect) but I find it plus the rest of WW2 ariel and navel warfare endlessly fascinating, especially lately the Pacific theater with such great planes as the Hellcat, Corsair and Lightning, must have something to do with all those Airfix kits of WW1 and WW2 planes I used to build as a boy.
P.S. Near the end of the war two Spitfires landed on an airstrip just outside of Brussels, the two pilots got out and shock horror they kissed and held hands as they walked away, one was an RAF fighter pilot and the other was his wife who was in the ATA, Air Transport Auxiliary and had just delivered a photo recon Spitfire, I think they then went on and had a much delayed honeymoon!