Changing names and language in Egypt

In the old days, children, every Jewish day-school had students with names like Andrew, Scott, and Jennifer. Just as common was the well-meaning Rabbi who would insist on calling them by their Hebrew names (Aharon, Shmuel, and Yocheved.) The reason? Why, the midrash of course:

"Did not Israel possess four mitzvot [while they were in Egypt]…: that they were sexually pure, that they did not gossip, that they did not change their names, and that they did not change their language." -- R. Eliezer haKappar, as quoted by the Mechilta

I confess to never quite understanding this Midrash. Perhaps you can help. One problem is that the redeemer himself seems to have had an Egyptian name. [More here] Another, is that it seems clear from the textual evidence that the Isralites did change their names. The names of the original nation of seventy that settled in Goshen are given. We also have the names of the tribal leaders who took part in the Exodus, and the names of a few others dignitaries. Not one of them is a repeat. If the Jews who were redeemed from Egypt understood this Midrash in the way that most Jews do today, wouldn't we find at least one Avraham, and maybe a Yosef or a Yehuda, among the dor hamidbar? Yet, we don't.

Writing this post, two other thoughts occured to me.
(1) The well-meaning Rabbi mentioned above also told us the Israelites were redeemed because they didn't embrace Egyptian clothing styles. This point isn't mentioned in the Mechilta cited above, and though I may have once known the source of this idea, I appear to have forgotten where to find it, and Google is no help. [Note to DovBear haters: Rejoice! Here's a new opportunity to call me ignorant!] Anyway, the textual evidence opposes this midrash, too: At the Exodus, the Israelites asked the Egyptians for gold, silver, and clothing.

(2) The Midrash above says the Jews were redeemed because they kept their language. For 2000 years, we spoke languages like Aramaic, Greek, German, French and Yiddish, yet it was only after (some) Jews made a serious effort to rehabilitate Hebrew that the State of Israel was established. Coincidence?