What does Faulkner achieve with his point of view and disruption of the chronology of Miss Emily's story? "A Rose for Emily" by William Faulkner

In "A Rose for Emily," the seemingly random revelations of
the townspeople/narrator enable the narrator to shock readers with a surprise
ending. 

Placed chronologically, Emily's poisoning of Homer
is painfully obvious.  Relating the events to the reader in a random manner enables the
narrator to surprise the reader with Homer's skeleton and the grey hair on the pillow. 
That is the direct answer to your question.  Of course, the events only appear to be
given randomly.  The plot is obviously carefully
manufactured.

The narration is the "we" of the town.  The
townspeople relate events from outside of Emily's home.  The narration tells only what
could be seen from the outside, not from the inside.  Bits and pieces of Emily's history
and actions--such as the buying of poison--are related to the reader as the person
involved might have related it to others.  Again, the pharmacist is an
example. 

The narration makes the surprise ending
possible.  The "we" relate only what they know at the time events occur during all of
the flashbacks that dominate the story.