My first answer was long and probably confusing. I also neglected to mention something PrintDriver brought up about converting from RGB to CMYK via the Convert to Profile menu options. If the printer asked for CMYK tiffs, yes, convert the RGB files to CMYK using that approach.
Photoshop does not make the photos blurry during the conversion, so I’m not sure what you’re seeing there. It’s also frequently helpful to apply a small amount of sharpening to the photos while still in RGB.
I never rely on exporting to PDF to do the CMYK conversions because I’d rather see the effects of the conversion on each photo one at a time rather than assume a batch process will work equally well across the board for every image. If you want to do it all at once with PDF, go right ahead — you likely won’t notice a difference. However, be sure your printer is OK with getting a PDF instead of all the packaged source files and be sure you include bleeds.
At the risk of confusing you more, your job isn’t just to plug photos into their spots. Part of your job, I assume, is to make sure the photos are prepared in a way that will result in the best quality once they’re printed. A conscientious photographer will tone his or her photos, but you can’t always depend on that. So it’s your job to make sure the photos are toned correctly and that the right profiles are assigned to it during the RGB to CMYK conversion.
Doing this means working with the photos on a good monitor that reliably shows what the photo will look like when printed. This means inputing the right color settings and choosing the right profile when making the conversion.
Since you’re putting together a catalogue, depending on the quantity being printed, there’s a good chance that it will be printed on coated paper stock on a web offset press, so, as PrintDriver suggested, select a Web Coated profile when making the conversion. However, we’re making assumptions here. It’s entirely possible that your catalog will be printed on, for example, a sheetfed press using uncoated stock, in which case, you should choose a profile that reflects that. The only way to know for sure, is ask someone who’s familiar with how your job will be printed.
A top-notch printer that is concerned about the best possible quality will supply instructions for all of this, along with specific settings. Sometimes, though, catalogues are just banged out with minimal care, so in those cases, you’ll just need to get the basic settings more or less right by choosing a profile that corresponds to the paper stock and the printing technique. Failure to do this could easily result in all your photos printing too light or too dark, which you don’t want to happen.