Is a department or agency entitled to impose conditions such as signing an acknowledgement form relating to the DOJ's Code of Values and Ethics as a condition precedent to management conducting an annual Performance Review and Employee Appraisal (PREA)?

No.  Departments and agencies are required to comply with the collective agreement obligations without exception.  A deliberate delay on account of the imposition of a condition precedent that is not already prescribed by the collective agreement would likely be viewed by the AJC as an unreasonable, arbitrary or bad faith application and interpretation of the collective agreement and therefore a violation of the collective agreement.