Dan.
Some interresting points that may indeed be inaccurate.

As you say a bat is not a bird, at least, it is not a bird by todays definition.
You must remember, these commandments were given to a simple people (by todays standards) some 3 to 4 thousand years ago with the intent of relaying Gods instructions in a way that they would understand. Would they have understood If it was said "of the mamals you must not eat the bat"? I don't know and cannot answer.

The insect with 4 legs that have feet is more interesting. Take a look at some pictures of grass hoppers and locusts and you will see 4 legs at the front of their bodies and 2 at the rear that are very different.
What is meant in the text by the statement "which have legs above their feet"?
Could that be refering to the fact that the rear legs have feet that are behind the legs?
Maybe, and with that in mind the rear legs of the beetle also have backwards facing feet. Indeed, maybe the answer is as simple as, the israelites only counted the legs at the front of the body?

Dan, if the fact that we today classify those creatures as having 6 legs is enough of an inaccuracy for you then fine. However, I am not at all convinced that our way is the only way of classifying legs, especially when there is 3 to 4 thousand years separating us from them.
I am not even convinced that ours is the best method of classifing them. Who's to say that in 50 years time science won't change its mind and begin saying that they actually have 4 legs and 2 of something else. It wouldn't be the first time that science has changed its mind.
Then I would be able to say that the bible was accurate all along and todays science was wrong.
That wouldn't be the first time that happened either.
Not so long ago, Archeologists used to deny the existence of the Assyrians.
But now we know they existed, now we know the lived just where the bible said they did
Now we know they were indeed as cruel as they were portrayed in the bible.
And so it goes, time and time again.
Anyway, I am not phased because the bible has not classified them in the same way that we do today.

I will, and have, conceed the fact that the bible is not a science textbook, especially in the light of todays science.