AWESOME BUT STILL SO MANY QUESTIONS?(WARNING SPOILERS!!)

Rating: 8/10 (8 November 2003)

When I watched this movie, i stunned with so many great special effect and good plot. However there so many questions still haven't answered yet..so i need all the matrix fans to answer and give me some explanation(WARNING!!!SPOILERS).Actually I have some questions:
1. When Neo and Smith battle for the last time, in the end, Smith "hack" Neo to spread his virus but why after that scene, Smith exploded and lost??Is it because of "balance and unbalanced thing" that Oracle told to Neo in the middle of the movie, so when Neo is died, Smith also must died?
I also would like to comment that i quite disappointed with the ending...because i thought that the war between the human and the machines will be massive (like the first war between human and machines in the Second Renaissance-Animatrix)and in the end only one race will survive ..but it is wrong..is it there is a possible that The Wachowski Brothers will make the fourth film..??but Joel Silver said there will be no more Matrix after this Revolutions... but overall, this is the great sci-fi movie.. and i think it is worth for all of u to watch it over and over