I guess the writer of the show decided to kill of sloan because lexi died and he had no reason to live. That's what my friend told me. LOL I have no idea, but I loved Mark. I hope that Arizona gets better. The first episode made me cry :(
It wasent explained. All it said was he was terminally ill? I never heard that before?
It was explained in the second episode of the season from my understanding. But I don't know exactly what it was, I didn't watch the second episode yet.