Pages and images

You can open them all in Preview and edit them in batch.

 

You can resize them all in Preview, then drag them from Preview into your document, then quit Preview without saving changes. No duplicates are created and the originals are still the same size. There may be a way to resize them in Pages, but I can't help with that, as I use MS Office.

 

Drag the images into Pages. They will overlap, it seems, but don't manually move them around.

In Pages, 'Select All' the images. Then go to the 'Arrange' menu. Play with the Distribute and Align settings until you get something you want.

With 'Select All' images still, go to the Inspector, and choose the 'Metrics' tab....it's the ruler. Set the size you want here. It will make all the selected images the size you set. If you want more than one size, then you will need to select the common images and do each group separately.

If you want spaces between the images you could resize the images to be a bit bigger than needed, then do the Align/Distribute thing, then resize to the final size. I wasn't able to figure out a quick way to leave spaces with the Align/Distribute menus. It may exist, but I don't know it.

More: Also, if you need more than one column of images, try adding columns. I haven't tried this, but I would think it would work.

Luck.