uh did you see how far away everyone was from gandalf??..........no one would have ever reached him in time.......and besides i think gandalf could have pulled himself up IF HE wanted to.
in the movie the balrog only pulled him off the ledge and the fire whip let go of him but in the book the whip dragged him down with the balrog
gandalf new that the balrog would be a great threat once the war of the ring started, so he knew that he had to atleast try and defeat it. much the same with smaug. smaug and the balrogs defeat were vital to the defeat of sauron. imagine what that balrog could have done in lorien or rivendale or maybe even if it was at the black gate, or worst of all the pelenor fields. and with smaug still there the dwarves would not have a strong hold in the north so saurons northern armies could have come south, and thats not mentioning what smaug could have done.
tinuviel he cudnt get himself back up. it makes more sense that he would have if he could have. and in the books he falls immediately, theres no hanging...
and orlis elf, tho bein the white wizard is higher than the other 'colors', i dont think u get the sense in the books that the hierarchy is a rigid promotion deal. i guess what happened is gandalf went back to heaven and was reborn as the leader of the istari (wizards) whose purpose is to defeat sauron. saruman had given up his position as 'the white.' sorry if tis aint a too good explanation, but...