LR is roughly equivalent to Camera Raw, converts raw format to some standard workspace. Therefore there is no need to ACR when exiting from LR to Photoshop, the conversion is complete. The CR filter in Photoshop has nothing to do with raw conversion, just supplies the CR interface for editing.
I don't know of anyway to use LR for cataloging only, with the intent to go from LR to ACR to Photoshop. And there is no need, anything you can do in ACR can be accomplished in LR. And it uses the same camera and lens profiles.
First of all uncheck "use graphics processor" in ACR preferences. This will take care of the display issues. You can access ACR preferences from ACR or Bridge.
What happens when you "Edit in Photoshop" from Lightroom, is that a script reads the Lightroom settings and passes those settings on to ACR. The file is then processed silently by ACR and opened into Photoshop. Silently means that the ACR interface never opens. There's no need, since the settings have all been made in Lightroom.
For this to work, the two need to be in version sync. If they're not, you need to export a rendered RGB file from Lightroom into Photoshop. The net result is much the same, but nowhere near as streamlined and flexible.
You can work the way you want, but it's pretty convoluted and complicated if you ask me. You need to set Lightroom preferences to always write metadata to files (in addition to the catalog). This way you can quit Lightroom, go to Bridge or your file browser, and open them directly into ACR with those settings.
Or you can open as Smart Object into Photoshop. The embedded smart object (the raw file) will always open in ACR.
Thanks for answers. It explains why I don't see ACR interface module.
Thats no problem as long as it is recognising my Camera/lens combinations - I was concerned as when I Import to LR I tend to convert to DNG and was unsure if it was picking this up.
I have the Metadata settings you mention for Catalogue but can't find anywhere to set it automatic for files (I don't want xmp files all over the place). This may explain why I often have to 'update metadata to files' manually after editing in PS - but not always. I save edited files as PSDs - could that explain anything?
I don't find it a convoluted workflow. I'm far more familiar with PS manipulation than LR Develop but use LR for cataloging - not Bridge. It seems you are suggesting a better way is to use Develop for basic manipulation and then PS for more complex work ? ... I tried that years ago and didn't like it (can't recall details of why now) but maybe I'll look again as I know LR Develop has improved greatly over that time.