Well, the first thing to take in account is that the clubroom is full of closed space. It's not that Itsuki can read minds at all, but rather that he's very perceptive. It's very easy to read Mikuru, and he can tell when Yuki is doing something behind the scenes, but not particularly what. Through a certain logic, he can guess what they're doing, but he doesn't actually know.<br/><br/>Seeing as every character has their own motives, such as how Asakura tried to kill Kyon in S1, I don't see why Itsuki has to be confined to what he has done in the past. Itsuki has always been a questioningly agreeable character, and I want to give it a reason. And the function of his character has also been to assist Kyon in catering to Haruhi, so when Kyon and Mikuru start to see eye to eye, then that's a problem for Itsuki.<br/><br/>With Mikuru, since we don't know all that, you can probably make up some of the stuff. I think young Mikuru actually doesn't contact her bosses often and only for the essentials and seems rather clueless altogether. Whereas older Mikuru just knows everything (don't forget, you get two characters for the price of one). Though, if she could simply communicate with normal objects, like mirrors, that could be interesting too.