Dear Somik,
regarding your questions:
1. required for the requests to be created. SAP delivers reqtype 011 with action retain.
2. This is used to classify the requests dependend on their priority. I have seen such set ups in environments where you run UAR for productive system and also others (development, test, quality, etc.). Different landscapes used different priorities.
3. Rejection reason: e.g. "User does not belong to me", "User account is not required any longer", etc.
4. SLAs are used as a management instrument to report the UAR (it also helps to identify long runners, etc.).
5. Failed to search.
Please check:
Regards,
Alessandro