It has been interesting to read the discussions about publishing and the OGL going on right now across the interwebs.
I'm interested because I'm literally dealing with similar questions right now.
I plan on using the OGL for my Barrowmaze Megadungeon. I'm specifically wrapping my mind around Section 6:
6.Notice of License Copyright: You must update the COPYRIGHT NOTICE portion of this License to include the exact text of the COPYRIGHT NOTICE of any Open Game Content You are copying, modifying or distributing, and You must add the title, the copyright date, and the copyright holder's name to the COPYRIGHT NOTICE of any original Open Game Content you Distribute.
So, by my limited understanding I must include each and every Section 15 (in their entirety) in my own Section 15 for each piece of OGC I employ. Correct?
So, say for example I've pulled OGC monsters from the Labyrinth Lord Core Book, The Advanced Edition Companion, the S&W Core Book, the S&W monster book, The Tomes of Horror I, II, and III, as well as various OSR modules and blogs - I will have a ginormous Section 15. Moreover, this section could potentially be filled with material that I don't even use in my dungeon but need to include to stay within the confines of the license. If that makes sense. God help the people who have to cite my Section 15...