you might provide a link to a good Build Engine Source Code FAQ.
Things didn't work out like I expected. Only a small handful of people have actually worked with the Build Engine Source Code. I wrote a lot about BUILD in my BUILD.TXT and BUILD2.TXT files. I don't think there's much else other than hints in the release notes or change logs of these modern ports.
is there any good FAQ in the net, which deals whith questions
like "How does Build Engine or it's related software (like SLABSPRI voxel editor)
[do something]?"
SLABSPRI is not a popular utility, so I don't think anyone ever wrote a FAQ about it. The source code is released, so maybe you should volunteer to figure it out and write something about it : ) Or, if you don't like wasting time, try using
SLAB6 instead.
There are links to many FAQs about the editing tools here:
http://www.polarismapcentral.com/Misc/Duke3d/duke3d.asp