Dear petermanna,
The reason why Jehovah's Witnesses don't want you to study anything but their literature is that they can't without their own publications build up a mind control trap. The teaching publications are so cleverly planned that they will lead you to the right conclusions from their point of view without you even notising if you don't pay any attention to it (which you have now done). They make it appear like you'd have made your own conclusions and desicion to join by doing a lot of 'personal' study even though that is NOT in fact a case. That's why they don't want you to study anything else but their stuff because their religion doesn't stand the true biblical, historical or analytical scrutiny or research done by the help of the outside material or sources including their former publications. Their teachings may look well balanced but that's very seldom so.
The other reason is that they consider that all the outside material are from the Satan's camp. They use this also as a threat by implicating that ''if you want to please God, which you surely do, don't you? Well, if you do, wouldn't it be safer to use the publications of the God's organisation than Satan's?'' This is what happened to me and I did that mistake and did not study anything but WTBS's material which lead me think that I had studied everythin and throughly. I had only considered their overly positive selfimage which was everything but true or factual. Don't allow this happen to you!
What it comes to ''the two witnesses'' of Revelation, they apply it to themselves. That verse relates to the prophets Eliah and Moses and their now a figurative prophetical role in the connection to the remnant, i.e. the discreet and faithful slave class. In other words, the JW's and their Governing Body claim to have that prophetical role of Moses and Eliah to the modern day world. This is how they DO consider themselves as those above mentioned prophets of old. And that period of 1260 days is the time period from December of 1914 to April/May 1919, if I remember correctly, during which time their work was under banned at least in the US and Canada. The whole time period got it's highlight in early 1918 when the leaders of the WTBS were sentenced in prison. After that their work almost stopped and they were in troubles. That's why they had their ''sack clothes'' on and died in a figurative way under the ridicule of other people until God gave them his spirit in 1919 and they came alive again and started preaching. That's the JW interpretation as far as I know. But this egocentric view is very easily shot down. From the following sites you'll find very good information: http://www.geocities.com/osarsif/index2.htm and http://www.jwfiles.com/index.htm and http://www.geocities.com/Heartland/2919/index.html and finally http://www.ultranet.com/~comments/index.html
Hopefully this helped you a bit.
L.
__________________________
This is the noise that keeps me awake
My head explodes
And my body aches
-Garbage