My weak suit is modern church history, and the D&C. I had a dim recollection that the appearance of Elijah came on the heels of Joseph and Oliver taking the sacrament within the Kirtland temple, and yesterday, sitting in the back of Primary, I finally took the time to look it up.
D&C 109 and 110 make interesting reading in light of our adventures of the last two years. In the temple context, we're told to seek wisdom in the best books (see also v. 14). The temple will be full of glory, because it will house God's presence (cf. Isaiah 6). Angels are sent out from the temple. Day of Atonement image. The church is a woman (like OT Zion). Joseph and Oliver take the sacrament (in the heading to D&C 110; cf. Leviticus 7:11ff) and then they see the Lord (cf. Exodus 24, with very similar imagery) -- I think this is the first zevach hashelamim (Lev. 7:11) of the Restoration.