Hi cantleave
I think you've put your finger on some legitimate problems within the JW faith and you're getting some of the exact same lame excuses that everyone gets.
You point out the obvious truth that predatory animals eat just exactly what they were designed to eat from the beginning. The idea of an all vegetarian ecology is a fairy tale invented by St. Augustine. And even if you were to forget predation entirely, scavengers who eat dead bodies are an integral part of the decomposition chain and this alone violates the Witness concept of "original purpose." (Although paradoxically, it is sometimes praised in the literature as evidence of a wise Creator.)
There are people that will tell you this is a problem with the Bible rather than a problem with doctrine.
Bunk! The restoration prophecies of Isaiah were never meant to be taken literally. Eating dust (Isa 65:25) is not a form of vegetarianism. Even if they are taken literally, predation is only foretold to cease on domestic animals (e.g. Sheep, cattle and goats.)
Many people in your position are troubled when the leaders and policy makers within the JW faith demand the respect that would accompany Divine inspiration, but they are unwilling to accept any of the responsibility that would go along with it. (i.e. If you're inspired, you can't be mistaken.)
There are people that will tell you that this is a problem with all religions
Bunk! Other religions certainly have their problems, but those that do in some way assume the status of prophet are very careful when and where they don this mantel. For example, the Mormon church claims to be spirit directed and claims to have a prophet. However actually speaking in that capacity is a relatively unusual event. Witnesses love to poke fun at the Catholic doctrine of Papal infallibility, but everything the Pope says does not carry ex cathedra authority. Like the Mormons, it is unusual for the Pope to speak in that capacity.
In contrast, the Witnesses draw no such distinction. Everything that is printed in The Watchtower is presented as the Truth without equivocation. Openly disagreeing even on minutia carries a significant risk.
There are people that will tell you that this was even a problem in the 1st century.
Bunk! The example they always cite (John 21:21-23) "This saying went out among the brethren that this disciple would not die" is a perfect example of this distinction. There is absolutely nothing to indicate that this "saying" was accorded the status of inspired teaching. There is absolutely nothing to indicate that 1st century Christians were forced on pain of expulsion to accept this "saying." The two situatios are not parallel at all and the Witnesses are simply dragging the reputations of the Apostles through the mud to make themselves look better.
You mentioned that you like science. You might find some of these amusing:
http://www.jehovahs-witness.net/jw/friends/140892/1/JW-Science-Quote-Of-The-Day-8-26
http://www.jehovahs-witness.net/jw/friends/140936/1/JW-Science-Quote-Of-The-Day-8-27
http://www.jehovahs-witness.net/jw/friends/141006/1/JW-Science-Quote-Of-The-Day-8-28
http://www.jehovahs-witness.net/jw/friends/141043/1/JW-Science-Quote-Of-The-Day-8-29