Help with conditional format or time formula

Can someone point me in the right direction please. Attached is a sample project plan, and what i want to do is either :
1. compare two dates and return either a color ( red, amber & green) Green when task is complete. Amber when 7 days to go & Red when past date.
2. same as above but have on, Complete,Due or late
3. A combination of the 2??

Any help much appreciated...and any other suggestions....