First of all, you should read through the man-page of adduser. Amongst other things it says this:
---cut---
Changing the default values
When invoked with the -D option, useradd will either display the cur-
rent default values, or update the default values from the command
line. The valid options are
---cut---
I'm quite sure you'll get answers to your other questions from there too..just start up a terminal/console and type
man adduser
and press <return> and you'll get what you need. I suggest you first read through the man-page of some command (and perhaps do a search for older posts in here) before posting a new thread...it's faster
