Semitic Language Attributes

According to Mormon 9:32-34 The Book of Mormon was originally written in a language called Reformed Egyptian, which was adapted from Egyptian.  Egyptian is now a dead language, meaning nobody speaks it as their primary language.  The written language of Egyptian was primarily used as a scribal or shorthand language, meaning one could convey more or less the same amount of information in much fewer characters.  This, Mormon indicates, was the reason they chose the language, because they were writing upon plates of gold, meaning space on these plates would be very precious.  Not only was the ore hard to come by at times (Mormon 8:5) but writing the history in their native language of Hebrew would have greatly expanded the size of the plates and thereby reduced their practicality.
Mormon also said that nobody but they used Reformed Egyptian, which was why the Lord provided a means of translation (the Urim and Thumim).  But, since we know it was based on Egyptian and Hebrew, we also know that it was a Semitic language, which is one of the major families of languages in the world, of which Hebrew and Arabic are the only ones still spoken today.  Now, the first language that the Book of Mormon was translated into in our day was English.  However, it is often evident when a text is translated from one language to another, especially when great care is taken to preserve the exact meaning of the original.  So if the Book of Mormon was really translated from Reformed Egyptian, we should see some evidence of this.

The Question:
What evidence is there that the Book of Mormon was originally written in a Semitic language?

Witnesses of the Book of Mormon

In matters legal, historical, scientific, and religious, we recognize the significance and the importance of first-hand accounts, also known as testimonies or witnesses.  The scriptures frequently tell us that "in the mouth of two or three witnesses shall every word be established" (see 2 Corinthians 13:1 for example), and the Lord's Church and His Gospel are full of instances in which this pattern is followed.  Among these are the testimonies of the witnesses of the truthfulness and divine origin of the Book of Mormon.

The Question:
Were there witnesses who saw the Gold Plates that the Book of Mormon was translated from, and are their testimonies dependable?