In which tabels the Roles, Usernames, Transaction codes, Change Queues

Hi All,

These questions are based on basis:

WIl any one tell me where the Roles, User Names for that role, tcodes, change queues are stored.

how they interlink to each other, how can we find the single and composite roles in the table. how can we find what time it is created and when it is changed.

how can we find how much time the request in change queue....

Thanks,

Ravi