Regarding to legendary drops, something very weird happend to me yesterday:
I was farming Act 3 in the morning when I got two (useless) legendary drops within a small distance. Now the weird part: Some hours later the exactly same legendaries dropped at the exactly same locations from the same monsters (not elite). The stats on the items were different, but they were both the same unique items..
Something tells me, that the randomness in this game is not so random ;-)