Makot Machlokes

What follows is a fast and furious summary of some of the better and lesser known arguments our rabbis had about the plagues.

UPDATED

1 - Did the plague of blood affect the Hebrews, too, or just the Egyptians?
Midrash (Shmos Raba 9:10): Egyptians only. And any water they touched turned to blood, too.
Ibn Ezra: The Nile only. Both Hebrews and Egyptians. Jews and Egyptians alike could drink from other water sources. The Midrash about twater turning to blood when touched by Egyptians, unless it had been purchased from a Jew, is discounted. [DB: This is also the plain meaning of [some of] the verses, and it makes some philosophical sense: The first plague hit the river which was an Egyptian diety [and its tributaries]. The point was to demonstrate the impotancy of the idol. Had any surrounding non-river water been affected the message would have been muddled.]
Radvaz: The Ibn Ezra is wrong, and you can't believe what he wrote.
Avi Ezer: "Everyone knows that the Jews got rich during the plague of blood [by selling water to Egyptians] this Ibn Ezra comment is obviously the work of a wayward student [talmid to'eh] who is poor in knowledge"
Rashi: Nile Egyptians only

2 - Did the magicians have the power to copy the plagues?
Rashi: Yes
Ralbag: No; the first plague affected entire bodies of water. All the magicians did was convert some small drops of water. [DB: And where did they get water if the Midrash above is correct?]
Abravanel: No, they had no powers. They just spread a rumor that they had copied the trick in private.
Samson Rephael Hirsh: The magicians were attempting to undo the plagues not copy them (would you really want more blood or more frogs?) and failed.
Robert Alter: Yes; in Exodus magic seems to be regarded as a technology of some kind, and one that works. [DB: Robert Alter isn't a Rabbi. I know]

3 - How long did the first plague last?
Rashi: 7 days
Midrash: 7 days
Chizkuni: For a very short amount of time, as indicated by the verse [7:21] The Egyptians could not drink *water* from the Nile because the animals that had died in it left the water foul and putrid. This also explains where the magicians found water.

4 - How did the frog plague start?
Midrash: The was one frog, which turned into many frogs after it was hit.
Rashi: Cites the midrash but adds a singular noun (in this case hatzafardeh) can be used to indicate the plural. [DB: What's bothering Rashi? The verse says Aaron was supposed to "raise up" the frogs by himself, whereas with the locusts (for example) the swarm ascended by itself. The verb for frogs is vha'al; at locusts it is v'ya'al) How could Aaron bring up all the frogs at once? The midrash supplies an answer.
Rabbi Eliezer ben Azarya (Sanhedrin 67b): One frog came up and whistled for the others.

5 - What were the tzefardaim?
Abravanel: Crocodiles

6 - What was Orov?
Rashi: A mixture of wild animals, snakes and scorpions
Someone else, forget who: Swarms of insects [Rational: There were two plagues that hit the river, two that were diseases, and two that his crops in the field. So why shouldn't their also be two insect plagues?]

7 - Which animals died during Dever?
Rashi: Only those left outside
Ohr hachayim: Only those left outside, and this is why the Egyptians were given a full day's warning.
Ramban: All of them, as the verse says, [9:6] All the livestock of the Egyptians died

8 - When did Moshe say the 10th plague would start?
Rashi: Exactly at midnight; davr achar he said around midnight so the an error in caluclating on the part of the Egyptian timekeepers wouldn't affect his credibility.
Mizrachi: Around midnight
Ibn Ezra: After midnight, in the second half of the night
Ramban: He didn't really say at all. Not exactly. He just sort of hinted.