And I know that I shouldn't be doing this on a shared
account, but I'm just playing around.
in reply to Programmatically Adding E-Mail Accounts
Buddy, if you "shouldn't be doing that" then "just playing around" is no excuse.
Unless you have root on the machine, adduser won't work. And passwd doesn't accept a password on the command line (it would be a huge security breach if it did), you'll have to use Expect;
As for the rest of your questions, they depend on the details of how the server was set up, and this is not the place to discuss them. You want a unix discussion forum. Go back two routers and turn left.