Sorry to bother you again with a quick question. I've imported all my old images, and groped the similar shots into stacks, and closed the stacks to reduce the number of images shown. Now I'm going through and applying keywords, but the keywords I select are only being applied to the pick of the stack, not the whole stack. Any idea how to apply the keyword to the whole stack? I've tried the "primary only" toggle and that doesn't seem to be it.

Yes, metadata should really be a stack attribute, not an image attribute, but there is nothing we can do about that. The real answer is to set up your workflow so that you stack last. Apple seems to think that doing it first is the way to go but my experience is the opposite -- there are just too many gotchas. Do absolutely everything you normally do to your photos and then stack them. Or better still, stack only the good ones. There is usually no point wasting time on the one and two star images taken at the same time: they are still accessible simply by displaying thumbnails in time order.

To quickly access stacks (and only stacks) to apply metadata, do this:

1. Open all the stacks with option ' (apostrophe)
2. Go to the top with Home
3. Select one image in the first stack and press command E. That extends the selection, selecting all of the images in the stack
4. Drag keywords from the keyword HUD and they will apply to all of the images in that stack
5. Hit option Page Down. That takes you to the next stack and selects all of its contents.
6. Repeat steps 4 and 5 as many times as you need
7. Close all the stacks with option ; (semi colon)