In absolute terms, yes. Within the context of Christian theology, the distinction remains. I'm not a theologian, but it seems that distincinction would be important in a debate over "The Character of God's Words", in terms of determining what can properly be considered "God's Words".
No. If one rejects the Bible as inspired, there's no problem with rejecting the 10 Commandments as well. So, while I'm not sure where you're coming from, if we cannot trust the writers of Holy Scripture to deliver at least the ipsissima verba (exact voice) of God, why should we trust them to accurately relate to us the commandments which He wrote?
Relatedly, the words in the New Testament which aren't "in red" should be (if one accepts the proposition of a divinely inspired Scripture) weighed with equal importance to the words which are "in red." If one does not accept the proposition of a divinely inspired Scripture, words supposedly spoken by God are as easily discarded as those which were supposedly not. One just has to come up with a theory as to why one is discarding said words, and PRESTO CHANGEO, new revelation is formed.
I don't know if that's relevant to the point you were making. Sorry if it wasn't.