Woah, woah, should've killed him? Wtf? That's a bit extreme. Don't forget Danzo was revered just as highly as the other elders. Hiruzen respected Danzo and Danzo represented the dark side of the shinobi that Hiruzen wasn't. I mean, it's Hiruzen's fault Orochimaru grew so powerful and was able to defect from the village. Danzo wouldn't have hesitated to stop him, student or not. He understood the importance of sacrifices
Danzo was still in his position even after Hiruzen stepped down and Minato took over. So I don't understand what you're even asking. Minato most likely respected Danzo as he should've. Minato probably would've handled the Uchiha situation differently but overall, he wouldn't have done a damn thing to Danzo