Hi,
A 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 go into each packet level-wise and provide options for internal and external assessments, thus paving the way for progression.
Now, about the performance management - it 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 degrees for performance management, and of course, it depends on the employee strength, domain, and business focus.
Melvin.