Exodus 20:12-26 - Gerizim or Hebal?

The next seven commandments don't quite call for in-depth analysis, as they are forthright and plainly spoken:

"Honour thy father and thy mother, that thou mayst be long-lived upon the land which the Lord thy God will give thee.
Thou shalt not kill.
Thou shalt not commit adultery.
Thou shalt not steal.
Thou shalt not bear false witness against thy neighbor.
Thou shalt not covet thy neighbor's house; neither shalt thou desire his wife, nor his servant, nor his hand-maid, nor his ox, nor his ass, nor any thing that is his." (Exodus 20:12-17)

Yet, even though these commandments seem clear enough, there has nonetheless arisen confusion over the Ninth and Tenth Commands particularly. Apparently, by the time of Christ most Jews chose to ignore or misinterpret the last two commandments, believing that an evil thought was not sinful until it was put into action. But this seems simply nonsensical. Why would God forbid us to "covet" and "desire," and include these as part of His Law, if the thoughts, in and of themselves, were harmless? And if He has already declared that we are not to "steal" or "commit adultery," why would He tell us we are not to "covet thy neighbor's house" nor "desire his wife," if these latter two commands were essentially the same as the former two? It seems clear to me that Commandment Six and Seven are completely different from Commandment Nine and Ten. Six and Seven are laws against external action, while Nine and Ten are laws against internal thoughts. And Christ Himself even clarifies this for us when He declares, "that whosoever looketh on a woman to lust after her, hath already committed adultery with her in his heart" (Matthew 5:28).

The last thing I'll mention about Exodus 20 is that an interesting disparity was brought to my attention of which I had heretofore been unaware. Apparently, after the Tenth Commandment (verse 17), in some ancient copies of the Bible, including the Samaritan, Arabic, and Syriac versions, there exists five verses which instruct the people to write the Ten Commandments on stone and erect an altar to God on Mount Gerizim. Many Bible scholars, including Benjamin Kennicott, conclude that the Jews possibly could have deleted these verses because of their dislike of the Samaritans and the fact that Mt. Gerizim is a holy site for Samaritans. Though other scholars, such as Antoine Augustin Calmet, believe that it was the Samaritans who doctored the text and inserted Gerizim into Exodus 20. The five "missing" verses in Exodus 20 can actually be found in Deuteronomy 27, where instead of Mount Gerizim, the people are instructed to house the Law and build an altar on Mount Hebal. Kennicott, and others, say that Hebal could have been inserted in place of Gerizim. Obviously, this is something we can probably never truly get to the bottom of (and I am certainly not any sort of authority on
Bible history to be able to cast my opinion in the mix). It's simply an intriguing issue to ponder, and ultimately it doesn't affect the meaning of the Word nor our salvation.