It wasn't stated they let Rin know about it, it was just stated that Rin knew about it. She could have gained this knowledge without Mist knowing about it.
Well, they had her captive, they sure are stupid, if they did it in a way, where they thought she wouldn't find out. Also as I said, they had her captive. We know what sort of techniques Konoha has. Like taking over people's mind etc.. It can't be just Konoha having such kind of abilities. Even if it's restricted to a clan, similar abilities must exist within every great village, or they'd be no match for Konoha. So they should had been able to do something, so the plan would go smooth...
Konoha could handle Kurama with NO MAJOR damage? It was the most damaging incident that ever happened in Konoha apart from Pain's attack. However, since Pain revived absolutely everybody after his assault, I would even say that Kurama's rampage was worse.
Not really, it's not like the village was "wide open" for attacks. Surely some died, but it's not like it did collateral damage to the village. Surely it was a terrible incident, since they lost a fine hokage, but he didn't really die, because of Kurama alone... So it's incomparable. Fact is still, if Minato would be around, he could move it out before a single person died. That dude must have several seals all over Konoha, and probably also at borders around Konoha. I bet every guard would even carry a seal, I mean it's the perfect way to defend the village. And people from Yamanaka clan can easily reach him very fast and call him. It's a matter of seconds before he is in control of the situation.
Sanbi might not have dealt as much damage as Kurama, but it would still be a hit to Konoha - an opportunity Mist could use to attack the village themselves.
Surely with right planning it could work, but seeing how it failed, it's just a ridicules plan, and it's unlikely to happen in the well made up narutoverse. It's actually contradictory to previous events thought up by Kishi..
No, I actually liked this explanation MUCH MUCH better than stupid theories about Rin being a spy or Kakashi killing her to protect intel.
Don't get me wrong. It's a nice idea, that they wanted to use her as a weapon against leaf, but the way it was set up was amateurish and stupid. I liked the idea of Rin being a jinchuriki, but kidnapping her and turning her into a jinchuriki in a short time seems stupid and unrealistic. I can think of many other ways, Kishi could have done this and came out with no problems for the plot or the time line. So unless he has a further plan with this, it's one of the most stupid ideas he ever came up with, IMO.