Jhn 3:14 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:
Just as Moses lifted high the snake in the deserted [places], in this way, there was a need for the Son of man to be lifted high.
The big shock here is that, in the Greek, the lifting up of the Son of man is in the past tense. The word translated as "must" is in the imperfect tense, meaning that the action was begun in the past. The infinitive translated as "be lifted up" is aorist tense, which is usually translated in English as the past tense. Specifically, in this conversation Christ has used the aorist tense to refer to the past, most recently in 3:12.
The KJV translates this verse to make sound like it refers to the future, that is, Christ's crucification, but it clearly does not.
Christ here is referring to his previous statement, that no man has ascended to heaven except that he descended from it. In other words, for Christ to know what is does about heavenly things, he was lifted up to heaven, which could only happen because he descended from it. This all refers back to his birth from the spirit as well at the flesh.
In KV translation, it almost seems like Christ is making random revelations about his nature and future, but in the Greek, the entire conversation fits together nicely.
καὶ "And" is from kai, which is the conjunction joining phrases and clauses, "and," or "but." After words implying sameness, "as" (the same opinion as you). Used in series, joins positive with negative "Not only...but also." Also used to give emphasis, "even", "also," and "just."
Μωυσῆς Moyses, which means "Moses".
τῇ ἐρήμῳ "The desert" is from eremos, which is an adjective (used as a noun) that means "desolate", "lonely", "solitary", "reft of", "destitute of", "bereft of", "unclaimed", "vacant," [of places] "deserted," [of people] "friendless," and "not gregarious."