1. kakashi can awaken MS from 2 tomoe sharingan, 2 tomoe not a problem, and eye protected by skeleton, it has extra protection when a giant stone crush him.
2. tobi in his own perspective is not evil, his idealism is create peace under his mass genjutsu coz he not believe ninja world that full of hatred. and we can see there is similarity about shishui and tobi philosophy, they wanna protecting village/world without anyone know their name, sacrifice as unnamed ninja. they can sacrifice others life to fullfil the mission. itachi also use shishui philosophy, he killed entire uchiha clan to bring peace but accused as a traitor.
1. No, it was a huge boulder, plus a ton of other boulders fell on top of him afterward. That would be more than enough weight to completely crush his eye.
Why would Tobi want some random Uchiha's eye that was alredy crushed anyway. He obviously has access to 49823049832 other eyes, and he is going to pick a random weak Uchiha? It doesn't make sense. How would he even know that he was there and knew who Obito was? WHY would he want HIS eye? As already stated, since his LEFT eye has kamui, his RIGHT eye would have a COMPLETELY different ability, that has nothing to do with space-time jutsu. It is like that with EVERYONE else, so it has to be like that with Obito. Plus we never see Tobi use MS, so how would Obito's crushed eye be able to have that jutsu with no MS.
WHY WOULD HE WANT A RANDOM YOUNG UCHIHA'S WEAK EYE? My god, think about it, like really, THINK about it. He has access to any Uchiha he wants, why OBITO? He didn't even HAVE Sharingan activated until very shortly before he died, why would Tobi be looking at him and want his eyes when he didn't even activate Sharingan until basically 5 minutes before he died?