hi - competency dictionary links with roles, career development and performance management essentially. Check with the R&R sheet and from there derive the list of competency clusters required by the business. The top down approach, is always from Roles and Responsibilities. Define the Competency Levels for the existing Roles in consultation with the Business Heads.
Ideally Competencies can be packaged differently Something like - Domain, Technical, Behavioral and Process. Define what needs to get into each packet levelwize and provide options for internal and external assessments, thus paving way for progression. Now about the performance management - its is more about skills gap analysis,training and assessments. 360 degree assessments sometimes may be quite comprehensive and might have operational difficulties if not administered properly (though implemented with technology). You can think about 180 degree for performance management and ofcourse depends what is the employee strength, domain, business focus...
Melvin.