Adding fuel
Don't want to speculate and won't, but since you're already doing it, here are some more questions (I have not seen the approach plates)
1) The weather: Is there a tower or some other facility on the airport that reported the weather or is in one of those automated things? In other words, is the official weather and the actual weather likely to be close or the same.
2) Apparently this was a second approach. Was weather the cause of the first "miss"? If not, what was?
3) If the first approach was missed due to wx, what change in the weather would cause the crew to attempt a second approach? How did they know the wx had changed? (see # 1)
4) Was there a mechanical failure of the aircraft or a powerplant? Was there any avionics malfunction?
5) What is the experience level of the crew? What was their training?
6) Was the crew properly rested?
7) Re the icing theories: Was the anti-ice and de-ice equipment functional? Was it being used? When was it last tested?
8) Were there other aircraft in the area that might report on actual flight/icing conditions at the time?
9) Did the aircraft appear to be "on course" at the time of impact?
10) Reference has been made to GPS approches. Was the aircraft equipped for GPS? Was the crew trained in GPS?
11) Someone said there were two pilots. Was the pilot in the right seat a trained professional or a (legal) seat warmer?
12) Did the aircraft have an autopilot? If so, was it being used?
13) Does the aircraft have an altitude alert system? Was it properly set?
I could go on and on but that's more than enough for starters. That's why speculation as to probable cause seldom offers any accuracy. I know it takes patience but we must wait for the NTSB to do its job.
Condolences to the families of the passengers and crew.