1. He is not in the government. He simply leads dissident members of the Likud party.
2. Israel could not invade Iraq.
At any rate, a regime change in Iraq is in the interest of the US and other Arabs states. As with the origional Gulf War, it is Israel which will have to give up something. In the origional Gulf War, the US forced Israel to allow Syria to occupy 4/5 of Lebanon and to not respond after being attacked. This not only destroyed the myth of ISraeli strenth but weakened ISrael's position. Moreover, the Bush I administration then bullied Israel into the Madrid negotiations and all but forced a change of government in Israel. What will Israel have to lose this time for the US to pursue its national interest?