Greetings
I haven't been doing this very long either, but what you are trying to do is already working for me so maybe I can help.
I started with the Small package. Just used the default settings, made the iso, and tested it in a vm, it worked. penetwork automatically detected my virtual intel 1000 lan card and installed networking. Have you tried that? I didn't have to load any drivers to get the lan up
As far as mapping drives, I use a simple script for that, there is a file in system32 called autorun.cmd, I add a line to run my script after the last command there (before 'end').
this is what is working for me, I'm sure there are many other ways to go about it and someone will offer some alternatives:
@echo off
:offline
sleep 1
if not exist "\\192.168.2.139\nas" goto :offline
net use n: \\192.168.2.139\nas
call nas.vbs
nas.vbs is a script to relabel the share so it doesn't have the ip in the name in explorer:
mDrive = "n:\"
Set oShell = CreateObject("Shell.Application")
oShell.NameSpace(mDrive).Self.Name = "nas"
there are different methods to edit autorun.cmd, the simplest for you at first might be to wait until the build finishes, then go to the Win7PE_SE\Target\Win7PESE\Windows\System32 folder in winbuilder, make the edit, then use the 'Create new Target Image and ISO' button in Finals | PostConfig to make a new iso that has your edits without doing a complete rebuild (which would remove your edits in that folder). You can also add your script into the system32 folder there if you want for testing, or use the Additional Files option for both files to preserve them thru rebuilds
hth