What is Emily Dickinson's view on death as shown in "I Died for Beauty—But Was Scarce," "Because I Could Not Stop for Death," and "My Life Closed Twice before its Close"?

In the first two poems you list—"I died for beauty" and "Because I could not stop for Death"—Dickinson approaches death in an almost casual way. In both poems, the speaker seems somewhat comfortable with the idea of death and treats it as almost an extension of life. We see the speaker engaging in fairly normal activities that seem to lessen the seriousness and intensity of what we imagine of death. For instance, taking a carriage ride in the latter poem or having a conversation and forming a bond with another person in the former.
In "Because I could not stop for Death," Dickinson describes Death as a gentleman who takes her on a nice carriage ride. She travels across her life, and when she reaches her grave, it is described as like a home:

We paused before a House that seemedA Swelling of the Ground – The Roof was scarcely visible – The Cornice – in the Ground –

The grave is "a House" with a "Roof" and "Cornice," which makes it seem just like her new dwelling place rather than like something threatening. In "I died for beauty," the speaker has a conversation with the person in the grave next to her who died for truth. They decide they are "brethren" since the two concepts "are one." The final stanza begins with the speaker noting:

And so, as kinsmen met a night, We talked between the rooms

This again figures the grave as a normal dwelling place for the living, where people gather to hold perfectly normal conversations with people in their family. The graves are their "rooms."
On the other hand, both poems also end with a statement about eternity and time that leaves the reader with a bit of a sinister undertone. The two lines quoted above are followed with:

Until the moss had reached our lips, And covered up our names.

We can only imagine how long their discussion lasted (years? centuries?), but we also know that at some point it comes to an end. The fact that their graves are now covered by moss also means enough time has passed that people living probably don't know them or remember them any more. That seems to be the true end of "life" or existence. Similarly, in "Because I could not stop for Death," the speaker wonders at the passing of time by saying:

Since then – 'tis Centuries – and yetFeels shorter than the DayI first surmised the Horses' HeadsWere toward Eternity –

Again, this speaker considers how long "Eternity" could be, but she also recognizes a sort of paradox (in that it feels like it's been forever but then not that long at all). Both poems reference the passing of time and the different conceptions of time that the soul may experience after death.
"My life closed twice before its close" stands out a bit from the other two poems. In this poem, the speaker seems to be talking about events in her mortal life that seemed like the end of her life—some tragic change: loss, the end of a relationship, etc. She begins:

My life closed twice before its close;It yet remains to seeIf Immortality unveilA third event to me,

The words "its close" seem to refer to her literal death while the other two closures seem to have happened while still alive. It's possible that the speaker knows when she dies, so that could indicate she is speaking from beyond the grave as the speakers in the other two poems also do.
The next stanza continues the central idea of the poem—that life can offer experiences that feel like death:

So huge, so hopeless to conceive,As these that twice befell.Parting is all we know of heaven,And all we need of hell.

The speaker wonders if death could be any worse, any more "hopeless," than her previous experiences. Again, this poem seems to take a different approach in considering how loss makes life feel like death, while the other two poems speak more literally on what might happen after actual death.