Fireworks does not handle cmyk at all, just rgb(a).
To preserve your cymk colors, your best option would be Ps > File > Scripts > Image Processor
Ps > File > Automate > Batch (with associated Action)
If using the Suite: Bridge > Tools > Photoshop (Batch and Image Processor options are there)
For simple batch saves- in Bridge: enable Open jpg as Camera Raw > Select Images > Open in Camera Raw > Slect All > then lower left hit Save Images for the Save Options dialog.
these were helpful suggestions ... and I just looked into them all briefly.
but Ps doesn't offer much in the way of batch "Actions".
there is no resizing command (?) ... and even in Bridge I would just like a option to
reduce a batch of images by percentage.
I might try just converting all files to RGB in Ps or CorelPP, then using Fireworks to do all the other batch commands.
Thanks for your suggestions (some of which I was unaware of), and I'll keep these tasks in mind for future projects.
Open the Actions Panel and click the Panel property icon, you should see a few extra Action sets that don't load automatically by default - namely, the Production set. Select that one and in this set are a few items to check out/scutinize/learn from to help create the action you need.
On another note, here's a link to an olden golden that makes use of Conditional statements that may fit your needs
Though I have not tried this with newer builds.