Glad you got Asato's route working for you!
I'm not 100% sure what you mean about the game guide though, unfortunately it's sort of a weird bit that's written into the game's code (like literally, in the text files), but it doesn't show up consistently.
Leaks' ending is a pretty short ending (no adult scene, no CG).
What issue are you having with the CG gallery? Normally when you click on a thumbnail in the gallery, it should show the full CG until you click again. Is it doing something else for you?