<< How exactly? >>
Some were forced out physically; their homes destroyed to make way for Israeli citizens (by the way, if you are a Jew living outside of Israel, Ariel Sharon will pay you $20,000 to pack up your bags and move to Israel so that you can settle on what IS Palestinian land and create an Israeli settlement) and others, although perhaps not physically forced out, left becuase they were not granted citizenship, they were disenfranchised and they essentially became 2nd or 3rd class citizens. Those who stayed (now called Israeli-Arabs) are without a doubt 2nd class citizens. They work for less money in the same jobs as Israelis and there is widespread discrimination against them.
<< Decide what? Whether Palistinians are justified in killing people to get their way? >>
No. I do not wish to justify any method of killing for political gain. It should be recognized, however, that Sharon and the Israelis as a whole are NOT peaceful innocents. They have as much Palestinian blood on their hands as Arafat and the Palestinians have Israeli blood on theirs.