I can field a couple of your questions in here, though its still valid that the game doesn't explain them.
Cambions are direct half-devil offspring; very powerful individuals, but not full fiends. I believe a Cambion doesn't quite benefits from fiends' functional immortality, but they don't really age like mortals either.
Tieflings are mortals with fiendish blood in their heritage, but not nearby. I think the *maximum* amount of fiendish lineage a tiefling can really have is 1/8: that is, three generations down from first contact. They are just normal everyday people, who express fiendish visual traits, and sometimes manifest a few minor powers, but no more 'potent' than any other mortal race.
As for the drow mess... I made a thread about that myself. Drow are a subrace of elves, full stop. Anything beyond that is social/personal/spiritual and is not apart of their race.
My halfling has "Lightfoot Halfling", "Halfling", "Female", "Custom Character", "Halfling", "Lightfoot Halfling", "Baldurian"..... Sooo... They really do need to fix up their tag system.
For the rest, all valid issues and concerns, well raised. My support.
