I'm newbie in OpenERP developpement, and i want to add some fields to opprotunity form view.

1) I want to add Picklist field for Stages.

2) I want to add new field of type float (coefficient), ReadOnly and it depends on opportunity's probalility on the timing of creation:

                    If probability <50% then coefficient == 1  
                    Else if probability >50% then coefficient == 0.1
                    Else coefficient == 0.5

Once the coefficient is calculated for the first time, it should not be changed.