It is possible that Cubase 7 will pick up the Cubase 6 preferences.
I would not recommend to copy them, though. Some things are changed and the Preferences do not correspond 100%. Better to start fresh and build your new Cubase.
Still, you should be able to import some (i.e. the keycommands.xml, various presets, etc.) without issues.
Here you can find a detailed list of the Preferences, it could help to find the files of interest.
Won’t harm the space-time continuum, but will kill your performance and will most probably cause crashes all the time. We’re talking of ALL your 3rd party plug-ins here, not just a couple.
32 and 64 bit plug-ins should be strictly separated and the 64 bit version of Cubase should never “see” the 32-bit plug-in path.
You could do the following:
Leave the Cubase 6 installation as-is.
Leave the 32-bit plug-ins where they are
Create a C:\Program Files (x86)\Steinberg\VSTPlugins_bridging folder (make sure to add this to the paths scanned by Cubase 6)
This is the folder where the plug-ins which are only available in 32 bit should go.
Install Cubase 7 64
Install the 64 bit plug-ins to C:\Program Files\Steinberg\VSTPlugins (C7 will “see” this by default)
Play around and see how C7 performs
Add C:\Program Files (x86)\Steinberg\VSTPlugins_bridging to the paths scanned by C7
Play around and see how C7 performs using the bridged plug-in
If you get decent results, you can keep it like this, (at your own risk) and see how it evolves over time.
If it doesn’t work properly and you can spot bad performance with the internally bridged plug-ins, there are two choices:
Get rid of bridged plugs by removing the path in C7 and putting them back to C:\Program Files\Steinberg\VSTPlugins
Try to find replacements or, if they are VSTi, you can always fire up Cubase 6, use them there and export to audio.
In this case, it is sufficient to remove the bridged path in C7 and have jBridger create its bridged (.64) versions in a new C:\Program Files (x86)\Steinberg\VSTPlugins_jBridge folder .
Add this path to C7. There is a little processing overhead that should be fine, if you don’t use many bridged instances.
Steinberg does not support bridging, with or without jBridge, though.
I personally decided to get rid of all 32 bit only plug-ins except one VSTi (which I eventually render before mixing).
Hope this helps.