The confusion of course is intentional. Evolutionists do not want to state exactly the terms of the theory of evolution so they can dance around and cover all the bases. A good example of this is punctuated equilibrium. When their precious bones showed that there were no intermediates, they made up (out of whole cloth) the theory of punctuated equilibrium. So if there is graudal change, they call it evolution, if there is sudden change, they call it evolution also. This is a very deceitful manner of argument and also makes evolution impossible to disprove.
Basically, I think you're exactly right. "Evolution" as such is basically impossible to disprove, because no matter what facts come up, scientists will alter their explanations accordingly and call the new explanation "evolution" again. Or they will say "look at what we've just learned about evolution!" (Interestingly, this raises the question of whether "evolution" is even really a "theory" at all, because theories are supposed to be falsifiable. And one is hard pressed to imagine what kind of evidence could ever arise which would cause scientists to say OK, "evolution" is wrong - short of God coming to earth and saying so, or the discovery of a crashed Noah's-ark spaceship with empty incubators which used to contain all the critters we know about, or something....)
But what this really comes down to is that "evolution" is little more than "materialism": "whatever has happened, has happened with no Creator, but due to naturalistic reasons". That's what "evolution" boils down to. I don't even think "the theory of evolution" is very interesting. Half of it is just the (completely boring) statement that some critters are more successful at having offspring than others, due to various reasons ("natural selection"). Big deal, who didn't know that? The rest of the "theory" is just the statement: "And that, children, explains completely how all species have arisen." And I don't even think that whether one believes this second statement is important. I don't care whether children are taught to believe it, or not. I'm fine with them remaining skeptical about it or even doubting it altogether. It's not important.
One thing that bothers me about the "evolutionist" side is that they think it's so important, for some reason, that children in biology classes are taught to believe the statement "mutations and natural selection completely explain how all species have arisen". Who cares whether they believe this or not?
And this is when I start to suspect that what scientists are really in such an uproar about is that they feel that the materialistic worldview is being threatened. And that's when I start to lose sympathy for the "evolution" side, because I don't think it's schools' job to push a materialistic worldview.
Now, let me be clear, I think that scientists have to take the materialistic approach, because (to make a long story short) that's what "science" is, careful analysis of the world using repeated experiments and assuming that this repetition can tell us something, i.e. no one's gonna "trick" us. In fact, that's all fine with me.
The only thing that bothers me in this "evolution" debate is when scientists get their panties all in a knot and overreact to (very reasonable) proposals such as putting an "it's a theory" disclaimer in a textbook. It IS A THEORY!! What's the problem?
Say what one will about "creationists", but it reaches a point where the "scientist" side doth protest too much, and it really irks me. Best,