'kay, cool. I still can't see how the 'dead guy' follows him, him being some sort of ghost would be easy, but you wanted him to be a computer of some sort right? I don't quite know what to make of that though.. Not to criticize, I just don't know how it works. (it reminds me of Ryuk of Death Note a little bit :P)
As for the name of the protagonist, he doesn't need to be an exchange student right? If he is a native Japanese boy, I think it'd be authentic to give him a Japanese name, like Kenji. Same goes for his friend then. (the crazy doesn't need a japanese name i think)
And he hides his powers from the rest of the world, and hates Charly for bugging him and telling him what to do, while he likes having the powers. And Charly uses some nonsensical call word when activating a power for Kenji, sadly I have no ideas a call word. I'll keep it in mind though, if I come up with one, I'll write it down.
It's useful if we make a little habit for both Charly and Kenji then, something they enjoy doing, or just do, to give them some more personality etc. Maybe Kenji likes baseball or something, or has some kind of stop word he uses all the time (like Naruto's "datte bayo")
I think it's a good idea for the main character to be still in school, getting good grades, and having a nice life, until he meets Charly. The summer holiday has just started, so he doesn't have to go to school. Sounds good?