Nurse (in training) here.

Essentially the unclothed state can be attributed to hypothermia. Your body circulates blood poorly in the cold, less to extremities and more to your core to protect vital organs. The vessels constrict and valves are used to keep the blood in the core. When this starts to fail, your extremities are flooded with "warm blood" and you feel hyperthermic and undress.

As for the missing eyes, lips and tongues.. Scavengers. Those soft, fleshy tissues are easy to get to and free food.

Broken bones. Some are more easily explained. The smaller bones could've been the result of falls due to the hypothermia. Dizziness, nausea, confusion. A somewhat simple conclusion, I suppose. The chest fracture, not as easily explained, but maybe due to their weakened conditions, they were more susceptible to fractures. Family history of osteoporosis or other conditions could explain that, maybe.

Finally, there were reports of radiation in the area, I believe. I have no good explanation for that. But, ya know.. Russia.

Edit: /r/unexplainedmysteries has some posts on this that I think I've read before. Creepy might as well. On mobile or I'd link.