Are observing all anniversaries disallowed in Islam?

From previous experiences, I understand that 1) Celebrating Birthdays is considered Makruh by many scholars 2) Mourning the death of someone should be restricted to three days except for the closest relatives of the deceased But what is the ijtehad on 1) Mourning the passing away of very religious person like the grandsons of Prophet Muhammad 2) Observing "Urs" and holding food festivals in tombs and shrines 3) Celebrating personal events like wedding anniversary or some other happy occasion If possible, a daleel from the Quran and Hadith would be highly appreciated.