if i have already freed the slaves and been to ilmater's temple and unlocked 4 of the badge lock things but have not repaired the bridge or gotten the book on bridges yet, am i screwed with no chance to go further in the game?

if if were you, i'd use the CHEATERSDOPROSPER:Hans() cheat and put myself on the other side of that bridge and back. it may be the budlight talking but hey just think of it like casting a spell. a teleport spell with your computer. remember you need the newest patch. or use the team bg editor and stick the book in your inventory.

You should still be able to get the book and cross the bridge. I got all five badges, then went back to the Frost Giant Cave and it worked for me.