Hi there,
I have great experience building installers for windows, so, here I am.
Well, I usually use Inno Setup or WiX toolset to build installers, so, if NSIS is not a must, please consider my bid too.
For your project I'm planning to use Inno Setup because fit best for your needs. The code will be well commented and you can easily do further modifications.
If you need to see some samples of my work just let me know.
Best regards,
Sorin