Percentage Complete

I am doing a time plan as part of my a/s ICT course and i have status checkboxes to show the completion of a task i would like to have a % complete column to show how complete each tasks is.

From that result i would like to change the state box to green if 100%, to Orange if between 0-100% and , red if 0%

Checkboxes are linked to cells at bottom of sheet


I would like a "!" symbol to appear on th left of the state column if the current date is past the expected date to finish which is not complete


I am using excel 2007 in compatibility mode as my school has 2003