Can someone please tell me who and where Ilana came from? I do not remember her in any previous episodes?

She brought Sayid aboard the Ajira flight back in season five. As usual when answering questions I'm just gonna point over to Lostpedia if you want to skim it over to refresh your memory... ;) link

we have no real answer to that as yet....the only earliest memory i can recall is jacob visiting her in a hospital......her story has not been explained

She was on the second flight with the oceanic six. She was in 2007 with Sun and Ben and some others when Jack, Sawyer and Kate (and some others) werem 1987

Dun worry about her... she will explode into pieces xD