The main conflict is an internal one within Gabriel. Although he does have external conflicts with his wife and with a few others, the true conflict is internal. This is evident at the end when Gabriel sees his wife in a completely different light after she shares the story of Michael, a young man that courted her, who told her that he could not go on living without her if she moved/left him. Gabriel has his epiphany at this point when he realizes he can never love his wife like Michael did. He doesn't "have it in him," so to speak. Gabriel is a dynamic character because he does change by the end of the story. His outlook on life is very different at that point.
The setting (Ireland) is important to the work, yes. eNotes states that:
In his book, Joyce wanted to give the history of Ireland. The prominent characteristic he saw in Ireland, and particularly in Dublin, was the spiritual paralysis of its people.
The setting is not as important to this piece of literature, though, because the primary focus is on the characters for Joyce. The reader becomes immersed in the character of Gabriel and his wife and their struggles with each other and with other people in the work.
Both previous editors are correct here in identifying that the conflict is both internal and external, in that the characters represent different views or opinions within Ireland of the time of publication. "The Dead" is a very clever story for a number of reasons, but primarily because it works on a number of different levels. Not only does Gabriel suffer an inner conflict between the role that he plays and the Gabriel he would like to be, it is clear that he represents an opposing political school of thought to Miss Ivors, for example, and an opposing way of living your life to Michael Furey.
As the final story in Joyce's "Dubliners," a complex structure with much symbolism, that Joyce himself said he created "to betray the soul of that hemiplegia or paralysis which many consider a city." Gabriel's character is the final stage in a modern version of the ages of man. In Joyce's work, many characters play representative roles. For example, Miss Ivors of "The Dead" is Irish Ireland (western), Little Chandler represents the typical Revival poetaster, the harp personifies Ireland, Father Flynn the spiritually ignorant priest, whose past contains some unmentionable shame.
Thus, in this final story, Gabriel's conflicts are representative of many of the previous ones: the pettiness of life under British rule against the beauty of Irish Ireland, the compromising of oneself in the interest of getting ahead, the lack of self-understanding and understanding of others. At the end of "The Dead," Gabriel reaches this epiphany and feels "The time had come for him to set out on his journey westward." (Earlier in the story, Molly Ivors encourage Gabriel to go west and see the "Irish Ireland.")
His soul swooned slowly as he heard the snow falling faintly through the universe and faintly falling, like the descent of their last end, upon all the living and the dead.
In Dublin, the city of the British who control the jobs and wealth, the Irish soul "swoons" and the living are not in control. Their hope is only in a return to the Irish roots and independence which they have abandoned.