Your questions are not entirely straightforward to answer, Refiners Fire. The problem is one of definition. As one poster pointed out, technically a false prophet is anyone who makes a false prediction about the future. However, if I say, "Tonight I'm going to the movies" and something happens that prevents me from doing so, only a nut would label me a false prophet. There has to be predictions made in a religious context, or the concept of "false prophet" can become meaningless. Therefore in a Biblical context, we need to restrict the definition with respect to making predictions appropriately, to something like "someone who makes false predictions while claiming divine direction or inspiration". Note that "divine" can refer to any supernatural entity at all. This definition is in line with the notion of "false prophet" given in Deuteronomy 18. This definition precludes from being a Biblical false prophet someone who clearly indicates that his predictions are based on his own ideas not God's. One can simply dismiss such a maker of false predictions as a nutcase.
Another consideration is something that the Watchtower Society itself has pointed out, namely, that Biblically a "true prophet" is not just someone who makes correct predictions in God's name, but someone who in a more general sense truly speaks for God. Prophets like Jeremiah made plenty of predictions, but they also gave plenty of commands to the Israelites to quit doing evil and to obey God.
Given these considerations, I think that a good Biblical definition of "prophet" is "anyone who claims to speak in the true God's name". Thus a false prophet is anyone who claims to speak in the name of a false god, or falsely claims to speak in the name of the true God, and a true prophet is anyone who truly speaks in the name of the true God.
Note clearly: a claim of direct inspiration is not necessary. To make the claim of being a true prophet, one must claim that one's words are more than the product of one's own mind. One who claims direct inspiration is certainly claiming to be a prophet. One who claims "divine direction" above and beyond what one can read for oneself in the Bible is also claiming to be a prophet, because "divine direction" is inspiration.
With these definitions in hand, the leaders of Jehovah's Witnesses are most certainly Biblical false prophets. They certainly claim to speak in God's name by reason of their claim to dispense spiritual food from God to the household of Christ. They don't merely claim to read the Bible and interpret it and dispense those interpretations -- they claim that God gives them special understanding that is not open to anyone else. Thus they claim, not the passive sort of "divine direction" that anyone who reads the Bible can claim, but an active direction, one that results in their having understandings they could not have arrived upon aside from supernatural guidance. This is the basis for their claim of "spiritual authority" since 1919 over all who would worship the true God properly.
JW leaders make these claims not only directly but indirectly. They directly make them by such devices as the current baptismal vows in which the new convert agrees to obey "God's spirit-directed organization" (i.e., the JW Governing Body which speaks via the Watchtower Society) in everything and forever. They directly make them via various Watchtower articles which state in so many words that all elders -- including and especially the Governing Body -- are divinely directed when acting on behalf of the JW organization. They make them indirectly by claiming that anyone who disobeys or disrespects them is also disobeying or disrespecting God, who put them in their position of spiritual authority. A JW will almost certainly be disfellowshipped for stating that he no longer believes that JW leaders speak for God, and disfellowshipping is a public statement by the JW organization that a person is cut off -- not just from an earthly religious organization -- but from God himself because the person has sinned against God. Clearly, disfellowshipping a person for not believing that JW leaders speak for God is claiming that they do indeed speak for God.
There is an extensive essay that covers this topic in detail, with plenty of quotations from Watchtower literature going back to their very beginning, at the website http://www.geocities.com/osarsif/index2.htm under the title "The WTS and the End of the World". I also made a post several months ago about this, showing that J. F. Rutherford claimed direct inspiration by angels, but I can't find it right now (I'll look for it when I get a chance). You can also find extensive quotations (I borrowed from these for my post) at this link: http://www.premier1.net/~raines/guided.html . Good reading!
AlanF