QTR-Quadtone RIP

Yes, I should have mentioned this, although probably didn't in the interests of brevity. A regular soft-proof should work with any ICC, but preserve numbers must use a matching ICC - RGB or Grey. If you create your own ICCs you can opt to create both. Once you move to PS, I don't see the point of keeping an image in RGB, since the file size is roughly 3X. I'd convert to GG22, and then you can do a preserve numbers with the greyscale ICCs. The only reason I'd keep an image in RGB is if I did the B&W conversion in PS and want the ability to revisit it.

As a general principle I prefer to do as much of my editing in the RAW converter as possible, either LR or C1, especially for online use and large image runs. But anything I'm going to do a fine print of will almost always be fine-tuned in PS. That's especially true for B&W, but I tend to do that even for colour, as I feel that I have more fine control in PS. LR has a good reputation for colour printing, as it has PK sharpener built in and you can resize on the fly, and you don't need to generate a TIFF to print. But once in PS I don't bother going back to the raw converter to print, and on Windows you can't print to QTR direct from either LR or PS anyway.