2) teacherxstudent (affectionate, but not in love)
3) teacherxstudent (sexual)
Since Madara is Itachi's teacher, this pairing is just damn awesome. Besides, it puts together two of the hottest Uchihas! (MadaIzu is still better, though.) It is, however, unknown when Madara was Itachi's teacher. This leaves fanfiction writers to be creative, hence the pedophilia possibilities.
2) Lily's MadaIta pictures are so funny, AND hot!