1)
What is the meaning of "Pharaoh Chafra"?
1.
Rashi citing Targum Yonasan: Broken Pharaoh. The Ches serves in place of a Hei 1 .
2.
Radak #1: It is a nickname for the Pharaoh at that time.
3.
Radak #2: The Ches serves in place of a Hei. This is like Pharaoh, but the last letter is moved to the front. He will be Paru'a (exposed), like "Ki Fera'o Aharon" (Shemos 32:25).
1
I.e. this is like Hufra (interrupted). (PF)
2)
What is the comparison to Tzidkiyah?
1.
Malbim: Nebuchadnetzar will come until Egypt, and Pharaoh will be closed off in a siege, like Tzidkiyah was. Therefore, when he conquered it, he killed all the residents via his head slaughterer, like he did to Yerushalayim.