I don''t know where you got your information from, but every Quake game (1-3A) only uses Lightmaps, since lightmaps act as both the lights and the shadows.
You have to merge the lightmap to the texture using multiply (you can preview this in Photoshop). Below are the images of some photoshop picts I made, one normal, 2 with multiplied light maps (mono and colored), and 2 with saturated lightmaps (mono and colored).
The orange blobs in the "saturated" colored texture was 3 different colors. Red, blue, and green. As you can see in the mono saturated image, gray, black, and white had no effect on the texture (not sure if OpenGL saturate works the same). The multiply textures, on the other hand, look great and how it should look.
Medium, normal light in a lightmap is neutral gray remember. In the quake series, the brightest light was drawn as black in the lightmap, and the darkest shadows were drawn as white in the lightmap. (maybe Q1 inverts the lightmap, don''t really know). For you, you would just concider black as darkness and white as brightness, and gray as the middle ground.
You don''t need a shadow map, since a lightmap acts as both. Using 2 different maps just to make lights and shadows is a waste of space and processing power in my opinion.
Some see the glass as half full, some see it as half empty. To me, the glass it too damn big.