if TNG were filmed on 35 mm, does that mean there's more visual information out to the sides which would enable the crew to re-crop it to 1.78:1 or some other widescreen, without cropping the top/bottom?
Not significantly. The shooting ratio was ~1.37:1, barely wider than the 1.33:1 (4:3) it was transmitted as. If you wanted widescreen, you'd still lose ~23% of the picture to do it, which I wouldn't consider worth it, since TNG was framed for 4:3, not 16:9. As you can see in the following link - http://www.ex-astris-scientia.org/in...ent_vs_tng.htm
- where they not only needed to crop
the small amount of TNG stock footage used, but also stretched