1. It happens. Not very often but it does happen. The ELT just sits back there in the rear fuselage and sometimes it is overlooked instead of regularly checked for serviceability or perhaps even inadvertently switched "Off" after having been switched to "Test." It is just another gadget and gadgets do fail. Perhaps in the final report they should tell us if it worked as designed or not and if not, why not.
2. I assume the bodies were found in the wreckage and not just lying around in the bush. Of course, yes, you simply want dead bodies just go looking in the bush by the side of the Agege Motor Road but that's not what we are talking about here!
3. You can call it whatever you like (and it may well be marketed as an "airliner") but to the guys flying it, the Beech 1900D would be very, very similar to a King Air, what it was basically derived from. The name "1900D" comes from the fact that it can hold 19 passengers, where even a small 737 holds about 100! There is no real comparison between the two except that, yes, they are both airplanes.
There's not much point in having to look up a lot of stuff to get it exactly correct and then educate you in what a Part 23 or a Part 25 aircraft is, what the difference is between small and large or light, medium and heavy aircraft, what rules different aircraft may be operated to and all that stuff. Please believe me that going to Obudu in a Beech 1900D will have been very different to going to London on a Boeing 747 although they might both be "public transport" flights. And, no, you will not see a Boing 737 operated as a small aircraft, ever! A Beech 1900D, maybe, odd as that might strike you...
The Mobil flight department, right there in Nigeria, has operated a small fleet that includes Beech 1900Ds for many years now, accident-free. There is nothing that makes the 1900D unsafe, just as there is nothing that makes the Boeing 737 safe, looked at simply as another type of aircraft. It has very much to do with the way each is operated and that can be a very complicatd matter indeed!
5. Yes, and? Red or black, on the rear fuselage or on the fin... All the rules say is that the number and the letters have to be a certain size, of a contrasting colour and in a general location. Upper right wing, lower left wing, somewhere or other to the rear on both sides. (You can look this up or just go and take a look to see all the legal variations on this simple theme.)
You may see a white airplane with black, red or blue, a black, red, or blue airplane with white or silver... This is a matter of absolutely no import whatsoever, describing the markings as having been at the rear, back or tail, since they are all loosely correct. If the markings agreed with those of the missing aircraft and it was a Beech 1900D I think you could safely put any discrepancies down to sloppiness. And that brings us to point number...
6. Have a look around. Do you see much bigger problems for the rather small and overworked Nigerian authorities to deal with right now than one small aircraft that crashed in not-very-puzzling circumstances? Dr Demuren is doing the best he can with limited resources and this crash is, perhaps sad to say, probably not something of great interest or import except to those who lost loved ones in the accident. There's nothing in it to suggest a flaw in the aircraft itself so that just leaves us with something wrong in the way it was operated on the fatal day, what we used to simply call "pilot error."