When translating from Greek to English (or between any two languages), we must understand that the understanding of, and implications present in, any given text in one language, are separate to the matter of simple translation into another language. That is to say, one must be able to serve as a translator, and also be agnostic to the beliefs subscribed to either by the speaker in the original language, or the target language. As such, the question of whether a translation is accurate or not has very little if not nothing to do with theology or worldview. Therefore, those who understand the ancient languages are equipped and able to judge whether a given translation accurately renders the source language into the target one. To that end, let's review the NWT of the passages provided.
John 1:1
εν αρχη ην ο λογος και ο λογος ην προς τον θεον και θεος ην ο λογος
In the beginning was the Word, and the Word was with God: and the Word was God.
The translation I've provided is accurate, since it respects the rule of Greek that when an anarthrous noun (no 'the') precedes a to be verb (here, "was"), followed by an arthrous noun (having a 'the'), such is an identification of the arthrous noun with the anarthrous one fundamentally speaking, and not an identification to the point of making the two nouns identical.
Let me illustrate by an English example:
The Word dwelt with man: and the Word was man.
Here, the second instance of man does not imply or mean that the Word is identical with "man" in general, but that He is of the same nature as they. Similarly, here, the Word was "with God" and "was God" without being identical to whoever the first instance of "God" refers to, namely, the Father: "The only-begotten of the Father."
The article ('the') in Greek simply does not work as it does in English. When is the last time you heard anyone in English refer to Jesus as "the Jesus," for example? Or for that matter, when is the last time you heard someone in English refer to "God" as "the God," even when they were not distinguishing Him from any false god? Such is the usage of the article in Greek, for just two examples.
To write anything else in Greek is to identify the Word as the Father.
Even the Latin Vulgate (translated by someone with more than simply an apt familiarity with both Greek and Latin) uses the Latin:
In princípio erat Verbum,
et Verbum erat apud Deum,
et Deus erat Verbum.
John 8:58
ειπεν αυτοις ο ιησους αμην αμην λεγω υμιν πριν αβρααμ γενεσθαι εγω ειμι
And Jesus said to them: Amen, amen, I say to you: Before Abraham was, I am.
The Greek is straightfoward, and the deliberate contrast between was and am is absolutely intentional—it's as clear in Greek as it is in English. Now while "I have been" is true of someone who simply "is" without respect to time (i.e. so that Abraham's being born before Him doesn't matter), it is not what the Greek actually says. What something says, and what it implies, are two separate things. What something implies should be left to the reader to discern, not hoarded by the translator, and left for the reader to only discover later, as something hidden or concealed and thought of no import by the translator.
Colossians 1:16
οτι εν αυτω εκτισθη τα παντα τα εν εν τοις ουρανοις και τα επι της γης τα ορατα και τα αορατα ειτε θρονοι ειτε κυριοτητες ειτε αρχαι ειτε εξουσιαι τα παντα δι αυτου και εις αυτον εκτισται
For by him all things were made, in heaven and on earth, visible and invisible, be it thrones, lordships, principalities, powers: all things were made by him, and for him.
As if it wasn't obvious, the point of this passage was to exhaust everything in existence — "all things, whether in heaven or on earth." The translation of "all things" by "all OTHER things" is not a translation, but is patently theological and absurd (not to mention novel and unheard of before the cult itself) and unwarranted by any passage in the entire Bible.
The New World Translation is not only not the "most accurate," but it is one of the least accurate I've ever come across. It reads like a translation by someone who knows neither Hebrew nor Greek, but has gotten their hands on an interlinear, and is interested in the Greek and Hebrew languages, and is 'living their best life' by convincing others they do know them.
If one word were to be used to describe the NWT translation, it would be "inconsistent" — I dare anyone to find a translation which translates the same Greek in more ways (depending on who is being spoken of—which violates the most basic rules of translation) than the NWT.
What the NWT implies is that to say Jesus created all things, or that all things were created by Jesus, or that Jesus is God as the Father is God also, is different in Greek than in English, and that in Greek, it's more ambiguous, whereas in both Greek and English, there is no ambiguity present whatsoever; they rely on the ignorance of the reader to get away with how they 'translate' what is present in the Greek.