Who is this man?
Radak: The 'man' who showed this entire vision to me, i.e. the angel that appeared like Nechoshes (refer to 1:7:4:1-5).
Why does it say "b'Tzeis ha'Ish Kadim"?
Malbim: He went out with Yechezkel to the east.
What was "Kav b'Yado"?
Radak: A flax thread, like it says above (40:3).
What is the significance of 1000 Amos?
Rashi: For 1000 Amos outside the wall, the river did not deepen (refer to 47:3:6:1).
How did he measure 1000 Amos?
Radak: He had "Kene ha'Midah" (40:3).
What do we learn from "Mei Afsayim"?
Rashi, Targum Yonasan: The water was only until his ankles.
Malbim: The water was paltry, like Efes v'Ayin. This hints to understanding of Olam ha'Atzeilus via Sechel tied to physicality ? it is almost nothing.