Place them as high-res tiff files.
When you export to PDF you can specify if you would like to downsample the images.
Reason for placing as tiff would b e you coudl repurpose that file for printing.or other devices.
No need to reduce the resolution before placing - you can do that on outpu then choose the resolution you want for that device.
Res for Ipad 2 = 1024x768 resolution at 132 pixels per inch (ppi)
As long as the images are 132 ppi then they should be fine.
Your document size should be 1024x768 (or vice versa)
Thanks, Eugene. I hadn't thought of TIFFs. Guess I'll still need to convert the profile to sRGB, though, so I can preview the effect before I create the PDF (or check via Lightroom's soft-proofing option, perhaps).
I'd have to extend the margins for print, too: daresay I'd have to upgrade to CS6 to do this. But I'm not expecting, at this point, that it'll ever be printed. (Of course, it could be a runaway bestseller and attract a print publisher, but I'm not holding my breath!)
You can set InDesign to convert the working profile to sRGB.
I wouldn't convert the profiles as it will limit the gamut for future reproductions.
I'd leave the gamut alone (unless you're making copies of the files?)
I'd leave as much as intact as possible. That will mean your images can be repurposed for multiple uses.
InDesign PDF export can handle
Resizing of images
Converting colour profile
There's a good article here with presets http://dirtywords.tv/2011/indesign-to-ipad-pdf-preset/
Thanks again, Eugene - and the article looks really useful (there are always unpredictable gremlins, it seems).
My master files (the raw files with Lightroom's processing as XMP additions) will stay exactly where they are: Lightroom makes it easy to export a version any time you need it. Of course, it would be better to have files, as you suggest, that could be used for whatever future purpose in this InDesign file. Otherwise, unless I export under exactly the same name, I'd have to re-import all 300 individually if I were to need a larger size. So I'll follow your advice, but use Lightroom's soft proofing facility to preview the sRGB conversion.