Yes, both issues have explanations
- The vomit is caused by "cave adaptation". Dorfs who have spent enough time underground will get sickened by sunlight. It's curable by spending lots of times outdoors, but it's not fatal. I just ignore it. Checking the wiki for "cave adaptation" should give more info.
- The "horrified" problem is caused by dorfs seeing remains of "sentient" beings in your refuse pile. These remains will also cause caravan members that see them to dump what they're carrying and flee, bringing the rest of the caravan with them without any notice. Seeing remains is reported as seeing the being get killed, even if the death happened years ago out of sight of the sufferer.
The solution to this problem is to dispose of "sentient" remains such that they won't be seen. This can be done via atom smashing, magma, or a pit in the ground. You can dump the remains, or build a separate "sentient" refuse pile (which is a fair bit of work, because there are many "sentient" species, and several refuse categories [at lease corpse under refuse and body parts under refuse]. Also, titans/forgotten beasts are not included in any accessible refuse stockpile setting, so if you use a "sentient" refuse stockpile to dump into magma, you may want to ensure they're sent to the regular pile by first "block all" and then add each of the "sentient" species you have encountered, and then, of course, remove those from the regular pile).
The reason I quote "sentient" is that creatures such as Reachers are included, even though their intelligence seems to be rudimentary at best.