Regarding BG2 manual, even with all that size a lot of useful information is missing.
One thing I dislike about D:OS is the complete lack of information about the various skills belonging to the skill sets either in game or in the manual (which I did actually look at). One of the first times I leveled up and had the option of putting a point into Witchcraft or Scoundrel I was left puzzled because I had no idea what skills those would give me access to. Technically I still don't as I haven't found whatever vendor happens to sell Scoundrel skill books.