Permissions Question

Those are some good questions; I've sometimes wondered about them myself.

mad_jew? (Since he's the expert on telling people to reset their permissions. )

 

repairing permissions returns the permissions of the system files to their original values.

also, don't concern yourself too much about the different users, they're there for a reason, shouldn't muck around with them usually (i.e. don't kill -9 kernel_task )

 

Here is a troubleshooting page from Apple's Support site. Although its aim is to solve issues, it also holds a lot of useful information, some of which may answer some of your questions.

As janey says though, don't worry to much about it. OSX handles all this stuff quite adequately IMO.