You can find me on IRC as mentioned above, or PM me, or just hand around the Programming section of the forums.
The DLLs basically control how the levels work. The .map files hold the terrain (at least the way it starts up initially) and the DLL controls everything else (unit placement, triggers, victory/failure conditions, disasters, etc.). We haven't really been able to make DLLs from scratch before, so most of the "new" levels reused old DLLs that were only slightly edited. Hence the lava in strange places like the old levels. The C++ DLL template project has now matured to the point where creating new DLLs for levels is becoming a reality. But now people need to know (at least some basic) C++ programming to make them. The project looks a little scary at first since there is so much stuff defined in it, but it's not actually that hard to work with.
The VOL files are archives of files used by the game. Most of them are resources, such as recorded voices, game sounds, the novellas, maps, and more. One of the most important to the game engine other than maps.vol is sheets.vol. Sheets.vol contains all the units stats, tech trees, morale modifiers, mines values and such. It basically controls many of the parameters to the game engine. Sheets.vol is also the only VOL file using compression, so the revolver program can't extract from the orginal vol file. There is a version of it packed with already decompressed files in the file forum. You can also find revolver there. That should allow you to extract all the game resources, view/edit them, and repack them into the VOL files.
