Danzo can say anything he likes it doesn't make it true annihilate in which fanfic so you have the scan. The fact that it took the help if Obito to do it because of his unique power. They also knew that if the Uchiha did what they did other countries would attack. Knowing what exactly by your logic some clan that can be a beaten by root rebelled.that's where your logic fails.
Keep dreaming everybody knew the power of the Uchiha clan and if a clan of their calibre rebelled it was over for the leaf.
Orochimaru on his deathbed please he didn't even kill him he made the statement cut up Orochimaru. Orochimaru tried a body takeover and got solo'd by a genjutsu in his own realm. So keep up with the fanfic.
Not really an issue in a drawn out war the Uchiha would've stomped the cloud low difficulty. The leaf were the ones that felt they'd be destroyed without the Uchiha because the leaf knew the internal situation. The problem was the Uchiha would likely help after any major obstacles were removed. Or they could just up and go with nobody able to stop them. Either way it's a win win for them.
Also it's likely the cloud knew also since they had inside help(assumption). Even with Hinata's thing they selected the day of Hinata's birthday to nap her and knew the Hyuga would be away. Konoha wasn't displaying clan secrets to them that's for sure. So it's highly likely they knew of the Uchiha isolation situation which would've been even more evident.
When the leaf gets "crushed" what exactly is going to happen when the army that is crushing konoha comes along the uchiha's place in konoha?, Just leave thme be?, Of course not them will try to crush them too.
As i said, what happens to the leaf directly affects the uchiha.
Well that's just your assumption. Cloud was fully willing to betray konoha knowing it could cause a war, knowing full well of the uchiha and the rest of konoha clans.