Preface:
AFAIK I am not a lawyer
1) No if it's listed in the
SRD you can only reference the ability/spell/feat/power/etc. by refering to the book and chapter. ie
Living Construct: See
MM, Chp X
2) Depends on who's got the better lawyers to decide in court, (or who can out-wait who). Essentially none of the fluff would be
GSL, you can refer to it, I imagine that you can develop entirely original "locations and denizen" of any places listed in the
SRD. But that would be about it.
3) Yes, you can say that X race has a tendency to be Y class (as long as Y class is one listed in the
SRD). If it isn't and it's one of
WotC's classes you can write them and a) ask if they plan on putting it into the
SRD or b) ask for a special license to use Y class. Now if it's a class from a publisher other than
WotC you will have to contact them inorder to reference and use their class. Because there isn't any lateral usage in the
GSL like there was in the
OGL (which is one of the big flaws
IMO)
4) If it's listed in the
SRD you can reference it, but you can't tell what it is. Only see PHB/
DMG/
MM Ch. X