For creators, Wikipedia lists the individual issues creators worked on but not what collections (if any) contain said issues (there are a few exceptions, like Alan Moore). Amazon is a little better, but it still often lists creators that only contributed to one issue or will omit contributors entirely.

For eras, I'm at a complete loss. If I know the title of a collection I can look it up and see which issues it collects, but I can't find anyway to search from issue/era to find trades. Like, if I wanted to read some Bronze Age Batman, I have no clue how to find collections from that era without knowing creators, which gets back to the Wikipedia/Amazon thing.

Also, does DC not collect stuff from between the end of the Silver Age to 2000? When I'm in a shop the Marvel/DC split is pretty close to 50/50, but whereas Marvel has stuff from every era DC seems to only have Golden/Silver Age and post-2000 stuff with three exceptions (The Killing Joke, Death in the Family and Knightfall).