Despite the expansion/morphing of language, the same words communicate something very close to the same thing they did in the past. There are words in the Bible which are no longer in common usage, but it's not difficult to find them. Thee's and thou's are used in writing for a good while after the KJV; comparing formal 1611 English and current slang "ain't" exactly a good comparison.
As for translating from Greek/Hebrew, there are difficulties involved translating. That said, the difficulties are not insurmountable, or no one would translate anything. At least those two Languages had not been popularly spoken for quite some time, so their "meaning creep" should have been very limited, at the least. They had been studied throughout the Middle Ages, though, in the classic literature, so denotation/connotation were determinable.
RE: blind faith--I read the Bible and learn what I would expect to find if it were true. I see said things in the world. I don't claim to understand how everything in the Bible relates to my life, but based on what I do understand, I find my faith reasonable.
You look at evolution. You learn what you would expect to find if it were true. You see (I assume) such things. You don't understand how evolution answers a whole lot of questions, but based on what you do see, you believe it. It's the same process.
RE: testy after teaching--I think I had the same day you had.
