Could anyone please forward me to some abundant source of information on realms' gods?

Aside from the books? :D
Well, I think there's a link somewhere here in SP about the Pantheon of GODS for humans and elves.
And for books I'd go with the Avatar Trilogy and Lord of lies and Crucible.

Try http://www.sorcerers.net/Fan_Worlds/FR/index.htm

http://www.geocities.com/Area51/Chamber/2596/powers/00Deities.html

Batchuer gave the link for the best FR 2E list I know if. Here is the Grayhawk 3E list. http://www.cmc.net/~rtaylor/greyhawk/gods/lists/