Vivek,
1. Not sure I understand. On an unmodified body, the sensor already has a UV/IR cutoff filter. The visible light photos with both lenses was done with an unmodified D800E, so there should be no UV/IR contamination.
2. The modified D800 used for the IR shots here, has the UV/IR removed and replaced with the 720nm IR cutoff filter on the sensor. So no spectrum below 720nm is captured - this would allow minimal visible light and no UV. So not sure where the UV contamination would be from
3. I also have a D800 converted to full-spectrum. I did not post any shots from this camera, but on this one, I agree, on-lens filters would be required for whatever spectrum you are interested in capturing.
4. Fully agree that the regular visible spectrum lenses do not hold sharpness beyond the visible spectrum. This is one of the special qualities of the CO lens - it corrects from UV all the way through 1000+ nm in the IR range.
5. On the WB, I used a custom WB. Same camera with the 2 lenses. Not sure why the WB differences are as much as they and was more of a question on my part. Thanks for the link, I will have a read. But again, the filter on the sensor is already cutting for UV/IR at 720nm, so not sure of the need for stacking filters on the lens.