Unfortunately your original question had to be edited because it asked multiple questions. Enotes only allows you to ask one question, so please remember this in future.
Certainly, many themes abound in this excellent short story concerning the sudden tragic death of the narrator's husband and two sons in a plane crash. However, a theme that is explored in much of the writings of the author is the way that the characters engage in a search for their own identity.
Shaila, the narrator of this story, is a passive character, and not just because of her grief. Having played the role of dutiful wife and mother for so long, she is then smothered by the attentions of those around her. As she remembers, this happened once before:
They remind me of when my sons were small, on Mother's day or when Vikram and I were tired, and they would make big, sloppy omelettes. I would lie in bed pretending I didn't hear them.
From this situation of being a passive character, Shaila gradually begins to find her voice and herself as the story develops and as she accepts the reality of what has happened to her. The silence that she had adoped for so long in her married life, along with her concerns that she never told her husband that she loved him, are symbolically destroyed when she throws into the waters where the plane crashed a poem concerning her love for him:
For him I let fall into the calm, glassy waters a poem I wrote in the hospital yesterday. Finally he'll know my feelings for him.
However, the most significant moment concerning Shaila's search for her own self and identity is at the end of the tale, when she decides to continue the work that she had started in leaving India with her husband:
A wife and mother begins her new life in a new country, and that life is cut short. Yet her husband tells her: Complete what we have started... I no longer know what we started, nor how to complete it.
Yet, at the close of the story, we see Shaila hearing the voices of her family and responding to them, striking out a new path and continuing the "voyage" with such an uncertain destination. Yet the biggest and most important thing is that Shaila, in response to these voices, "starts walking." She has found herself and her identity.
Many of these have alot of wording, plus I only have this account because I'm doing my brothers homework, Im a young teenager and he's in college.... yeah, I'm the smart one when it comes to reading responses(kinduh;) the story is about her batteling with the culture difference and still trying to deal with the fact that many people close to her lost their loved ones, and so did she(husband and two sons). Through the story she accepts the fact that her husband and sons died and finds her inner self while doing so.
DONT JUGDE! IM YOUNG AND IM NOT COLLEGE LEVEL(actually I am, and Im in middle school haha, yeah baby!) ok, hope it helps... probably not..;)