A Mixture and Division (4th plague)

This is post number 101, (which is special as we know from Chagiga 9; see Tanya Ch. 15, and Toras Menachem volume 2, this week's parsha letter 5, here, translation into English here (#4 on that pg.)  Thanks to all those that offer their criticism or praise of the posts, it gives me the encouragement to continue posting.

Rashi (8:17) comments in regard to מכות ערוב that there was a logical procession to the makkos following the order of making war.  Why does Rashi wait until the 4th מכה to tell us this principle?  And he cites his source from the Tanchuma, why do we need to know his source? And why does he only mention in specific how the frogs exemplified this way of waging war?  I found these questions and a bunch of others asked in Likutay sichos volume 11.  The approach developed there is that there is an interesting phenomenon and difference between ערוב and the previous מכות.  All the other plagues, the name of the plague is a description of the plague, blood, frogs, lice etc.  However, how does the word ערוב, a mixture describe the plague over here, a mixture of what?  Therefore, we must conclude that the main thrust of the מכה was indeed the mixture, the confusion, noise and turmoil that goes along with the mixture.  Why is this part of the plague emphasized?  Rashi explains that part of waging war is to cause the enemy to be confused and scared  therefore, explains this principle is seen in the plague of the frogs.  However, why is the name of the plague borrowed from this aspect and not the danger of the wild beasts?  Rashi points you to the Tanchuma, for it is there, not in the Rabbeh that it says that what bothered the Egyptians about the frogs was the noise, not the their presence.
It could be this difficulty of the name of the plague being non-descriptive caused the Rashbam to say that ערוב isn't related to the word mixture, rather the word ערב, evening, and explains the plague was wolves that attack at night (see article about the approach of Rashi vs. Rashbam here.)  And a third approach is that of  Rav Hirsch, who suggests ערוב comes from the word ערבה, wilderness, meaning that the plague consisted of wild animals.
The meforshim ask why only at the plague of  ערוב that the Torah stresses that it affected only the Egyptians and not Klal Yisroel, why doesn't it say this already at the first מכה.  There are various approaches (for the witch hunters, see what the Ridvaz (volume 1 #813) says about the Even Ezra, who says the first three plagues did affect Klal Yisroel.) .
In terms of the "inner dimensions" of the Torah, the Rebbe says that it is specifically in regard to ערוב, where the natural boundaries of the world are being broken, there must be an emphasis, a strengthening of the differences and separation of Klal Yisroel from the other nations.  The lesson is that it is especially nowadays, when people think that they are smarter and more humain than thousands of years of human existence and want to make a complete mixture of everyone in the world, to step over the boundaries of gender, race and culture, that we must build the wall between kedusha and the opposite, להבדיל בין ישראל לעמים.