I can tell you that the number of US troops in Iraq has never been more then 150,000 at a time and that the death rate for those serving in Iraq is lower then it is in the US for people of the same age group (the math was done in the WOT forum - I want to say it was by authored by Major Cee, but I can't find it at this time).
As far as exit strategy...
The problem is that people (mainly the anti-war crowd) don't seem to have any semblence of reality. No informed person in their right mind thought
this would take less then a decade, but for political reasons people like to pretend it should.
The US will be in Iraq for AT LEAST a decade.
The question should be how fast can we get Iraq to be a self sustaining government. I think giving it another 5+ years at the least is logical. Those
who have a bias against Bush, The US, Democracy, or what ever will say otherwise.