Any proof of what?
The fact that he can't solidify inside susano'o? Seeing as it's a solid mass of the users chakra, with little space in the center, I think it's pretty logical that obito simply can't fit in there...
The part about susano'o sword? Well, again this is pretty much based on the same principles minato used just that instead of FTG, you quickly spring a susano'o sword when the person is just about to touch you. Seeing as he has a sharingan, spotting the right moment isn't tooo hard.
manga sasuke has yet to figure out kamui's mechanics. so i think he would get stomped here.
its no problem for obito to simply outlast the susano and wait till the uchiha cant maintain it. only madara can compete in endurance
Bold is possible... though I'd find it strange seeing as sasuke's seen obito kamui quite a few times. In fact, Sasuke should be the first person to know the secrets seeing as obito transported him into his dimension at one point.