I will have to re-read the commentary and see if I read it the same way, i.e. that it was misleading. But we can't say it was intentionally misleading, although I didn't find anything misleading in it, unless he explicitly says that there is a word "Logos" in Mat 1:25, which he doesn't.
Which version is more reliable? The oldest unical versions of the Bible were uncovered in 1859, Sinaiticus and Vaticanus. Westcott and Hort uses them as the source (and so does NAB, NIV, etc.). One of the reasons KJV has it because it used Alexandrinus, which is reputed to be unreliable, yet sadly it is used by the EOC. Perhaps the Vaicnaus and Sinaitucs were lost before the 5th cenutry so Alexandrinus was the only one available, who knows.
One thing perplexes me: Wycliffe is the oldest verison in English (I think), ratker "litteral," yet it doesn't have "firstborn" in it. Given that Sinaiticus/Vaticanus were not discovere until past the middle of the 19th cenutry, I wonder which source was used for te Wycliffe version. We must be very careful when we say that "something is in the Bible," precisely because an average church-goer really has no idea how complex and confusing the Christian Canon can be. It's a real miracle we still believe in one and the same thing. :)
Of course it does; the issue is not the word or even whether it was a later insertion. Christ was a firstborn as a Jewish legal term, regardless of other siblings. This is another englishism you introduce, when you imply that since Christ was a firstborn, there have to be a "secondborn".
When an American mother introduces her children she might say: "This is Josh, my first...", and even if her speech were interrupted at that point by a malfunctioninig coffee maker, we'd know that she gave birth to more than one child. But that is because nothing legal attaches to being the elder brother in America. To a Jew that would mean an obligation to God and transfer of title. When Matthew mentions "firstborn" it is to underscore that in His earthly genealogy Christ is in the line of King David. Little would he know that 2,000 years later people not familiar with the Jewish law or the working of dynasties would read stuff into it.