1. 3:1 sounds like there's been a break, something has happened, and Benjamin calls the people's attention back.
2. It's easy to imagine this summons and response in 3:2-3 as a rite. Of course, he gets the same message as the shepherds in Luke 2. Like the shepherds, Benjamin is told that all people get the good tidings. It's interesting to note that shepherd is a traditional imagine in Israelite prophesy for the leaders of the people (see, e.g., Ezekiel 34, Zechariah 10-11), but I don't know what to make of that, that wouldn't be pure speculation.
3. 3:15 -- I'll say!
4. 3:17 -- previously we had Nephi saying that there was "none other name given under Heaven", save Christ (2 Nephi 31:21), and now Benjamin says the same thing, omitting the "under Heaven" bit -- "there shall be no other name given", period, except Christ, who is the Lord Omnipotent (=YHWH). Nephi separated out Yahweh in Heaven from Christ on Earth, identifying them and also distinguishing them by which side of the temple veil they're on -- Benjamin collapses them together.
5. Put[ting] off the natural man is an undressing / clothes-changing image.