I just don't see how the hardliners could ever be proven wrong. They were being completely segregated/discriminated against and even under surveillance. The proof was in the pudding for that side. They were out for blood at that point and had all the evidence in their favour that they were being pushed out.
Your plan includes maybes and hopes which if they don't pan out, would have lead to something much worse, and odds are it was going to happen given the situation I mentioned above. It was a super long shot. Danzo's plan was scummy but sure fire. Itachi was always a smart person. I don't think he would have done it if he felt there was a good chance it could have been solved another way even with Danzo's convincing.
Easily. If the Uchiha clan could be appeased without resorting to something as risky and violent as a coup that could have killed them all, why in the hell would they follow Fugaku? I remind you that not the entire clan were warriors. There were civilians and elderly among them got wiped out alongside the conspirators. The Uchiha were distrusted and resented, they weren't being actively persecuted, there is no reason to think they were beyond convincing.
My plan would have been a lot more reasonable than the indiscriminate mass murder of an entire clan. Danzō acted prematurely.
But they can't take over, Fugaku would still be alive, and if Konoha kills him there is absolutely no going back.
No one is going to accept Konoha sympthasizers/puppets as their leaders(and Itachi is like 13) when right before they were all willing and ready go through with a damn coup, this was a far far worst situation than when Madara lost support because the Uchiha were tired of war.
Even before some Uchiha guys were ready to throwdown with Itachi because they didn't think he was loyal enough and Fugaku had to stop it. Some outcast who is already mistrusted is now standing with those Konoha bastards telling us to chill while they have our leaders imprisoned?
Yeah the Uchiha aren't going to have any of that.
Sure they could have. If Fugaku and his inner circle were rounded up and replaced, they wouldn't have any power. Without leadership, the remaining Uchiha that wanted to rebel would have to be extraordinarily stupid to try anything.
If the clan obviously benefited under Shisui's leadership, why wouldn't he be trusted, especially if he had Hiruzen to expedite changes to appease the clan?
At the very least, even if it wouldn't worked (which I have a hard time imaging), it would have been worth a shot, especially when the alternative was purging the entire clan.
Has it ever been explained why he has a Kakashi doll?
I... don't think so, but now I really, really want to know.