As to No 1, what Chauvin did screwed white police officers all over the country and made their jobs so bad with defunding, hate, and guilty (racist) until proven innocent, officers started resigning all over the country. I could see officers hating him.
As to No 2, I saw the defense claim this. Even if it was a normal use of force, it became excessive, so I do not feel this changes the outcome.
As to No 3, GF was dead (he could not speak to this) and Chauvin would not self incriminate. If it had been advantageous for Chauvin to take the stand and address this, the defense would have done so.
As to No 4, you had a ton of video and eye witness accounts so establishing “what happened”, was not going to take long. It was not a complicated case due to the evidence available of the crime as it happened.
That is my take and just one person’s opinion, could be totally wrong.