Hi,
I've been playing around adding multiple accounts, and while I'm not 100% that the following will do everything you need, it might be close...
After you've added the newuser, you need to make it a member of the "wheel" group. This allows that user to su root (which means it can start the network, for example). Edit the file "/etc/group" and near the top add your new account to the wheel group...
wheel::10:root,user,your_new_account_name_here
Also, I've found the webcam and audio don't work with the new accounts (since only user and root have read/write access to it). One way to provide access is to make the devices owned by the wheel group (since you're now a member of this, this means you can use the cam). To make this happen on boot, one way is to add the following to the bottom of the file "/etc/rc.d/rc.local" (I'm not sure all of them are needed, but it works for me...)
sudo chgrp wheel /dev/video*
sudo chgrp wheel /dev/sequencer
sudo chgrp wheel /dev/sequencer2
sudo chgrp wheel /dev/dsp
sudo chgrp wheel /dev/mixer
sudo chgrp wheel /dev/audio
sudo chgrp wheel /dev/snd
sudo chgrp wheel /dev/snd/*
Hope that helps,
Best -Duncan.Do
p.s.
I think to get the "My Document", "My Music"... links to work, you just need to make the folders in your new accounts home directory
cd ~
mkdir Documents Downloads Videos Pictures Music