Understanding Code For Menu Windows

Hey all, you might have seen me around Slick Productions, but since they're down for TLC I thought I'd ask here (and subsequently realized I didn't have an account).

I'm looking to mess around with the menu windows, specifically creating a new/altered menu layout for skills that display the MP window (Magic and Lore offhand, maybe others). The code (for Lore/Magic at C1/5098) seems to load some data (from C2) , but I'm having trouble understanding it and was hoping someone here had some experience with it.

Also, does anyone know what the LDA #$82 | JSR $4EC2 bit at the start of the function actually does? It doesn't seem to affect the actual layout which is controlled by C1/50FB.