A. You can use the /e switch during the unattended installation to specify a program to run, e.g.
winnt.exe /u:unattend.txt /s:w: /e:"w:\servpack\update -u -z"
The above would be used to install a service pack after the NT installation (-u for unattended, -z for no reboot), however you may get an error and in setuplog.txt the following error:
Setup was unable to invoke external program
<drive>:\<directory>\<program> because of the following error:
CreateProcess returned error 3."
This is because after the installation network drives are no longer mapped and w: no longer exists. Any source files need to be locally stored to be able to be run and then with the /e use a local drive letter.