Q. Is the being in Genesis and Judges referred to as maleka Yahweh (angel of the Lord) yeshua Ben Joseph, or an angel? Or is this being Yahweh himself in theophanic form? Why did he stand in place of Yahweh at times?
A. The Hebrew word mal'akh is usually translated as "messenger," so mal'akh Yhwh can be translated "messenger of Yhwh, angel of Yhwh." It can refer to a heavenly being whom Yhwh sends on a mission. However, sometimes in Genesis and Judges (perhaps a few other places as well, such as Exod 3) the term seems to refer not to an angel in the sense of a lower-ranking heavenly being sent on a mission but to something else entirely: to a smaller-scale manifestation of Yhwh.
The mal'akh Yhwh in these cases is the same person as Yhwh, but not all of Yhwh. The idea is similar to what is described by the Sanskrit word avatara. So it's not that the mal'akh in these cases stands in place of Yhwh; rather, the malakh is Yhwh, but just not all of Yhwh. This mal'akh is a more approachable, more user-friendly, less overwhelming manifestation of Yhwh. Examples of this use of the term mal'akh are Exod 3:2, Exod 23:20-21, Exod 33:1-3, and Judg 6:11-14.
Q. What is the relationship between el and elhohim and baal and baalim in Hebrew canon?
A. The Hebrew words el and elohim mean "God" and are used to refer to the God of Israel, who is also the God of creation. But they can also refer in the Bible to other gods, who are worshipped by other nations. An example of such other gods is the god Baal worshipped by the Canaanites; in fact there were several Canaanite gods with this title (Baal means "master," so it's a noun or a title, not a name). It appears that some Israelites applied the title Baal to Yhwh, the God of Israel, which made the prophet Hosea very frustrated.
Q. Are Judaism and Christianity monotheistic or henotheistic?
A. Various scholars have used the term henotheism in many different ways. I think the most common use is the practice in which a person or community prays only to one deity, even though the person or community may recognize the existence of other deities. In this sense, I think it is fair to say that both Judaism and Christianity are genuinely monotheistic and not just henotheistic. For both Judaism and Christianity, there is only one God who truly is all-powerful, and other heavenly beings (angels, seraphs, etc.) are merely subservient to the one true God. Thus the existence of these other heavenly beings doesn't really impinge on the monotheistic status of the Jewish and Christian religions.