The Winter of 1942 saw the loss of Stalingrad and all that had been hoped for in 1942.
Germany was losing soldiers of experience especially NCO's and officers which she could not replace , she was running out of experienced soldiers and replacements.
The recovery of the position in Southern Russia was down to the leadership of a professional soldier who was given a free hand and who was provided in part with the 1st SS PAnzer Corp as a means to that recovery because its Commander had refused a direct order from the Fuhrer which would have led to its destruction and quite probably the total collapse of Army group South and the loss of all troops in Southern Russia.
Would Germany's fortunes be served better if Hitler could have been removed from any decision making process on the battlefield ?
Should germany have sought a seperate peace and on what terms ?
Certainly a " what if " question but 1943 was the yearof decisions in Russia , before Kursk it as still possible that Stalin would have made a seperate peace , after all do you think Stalin cared if America of Britain won or lost ?

Separate peace was rejected by all allies so this question is nonsense.

Not such much as you might actually think .
There was contact in 1943 which came to nothing , and the russian sought peace in 1941 before Moscow .
Hitler perhaps with good grounds refused to make a peace then.

Actually Hitler's stubborn refusals to not let the German army retreat during the winter's of 1941 and 1942 helped save Germany from defeat sooner. If the German army had tried to withdraw or fall back it would have turned into an all out panic in the snow than an organized retreat. The entire front would have collapsed.

In 1941 the decision to hold was proved to be correct , pockets supplied by air against minimal Russian air force and over short dustances proved possible.
The situation in 42 , should never have been allowed to arise in the first place.
The ability to supply pockets in these circumstances led to the thought that this was posible on a large scale , it proved to be completely wrong.
The stand order in 42 if obeyed would have led to the complete loss of Ist SS Pz. corp in Kharkov.
MAnstein withdrew forces in good order , the stand order would have proved wrong in 42.
Germany could have come to terms with Stalin and should have done so , he was open to a deal in 41 and could have been brought to the table in 42 , even up until Spring of 43.