Let's say I want to import metadata I've edited in Lightroom 4 to Bridge CS6
Can you be more specific to what you mean.
Metadata like IPTC and keywords is respected in both Bridge and Lightroom after adding it to the file, provided you have pointed both to the same folder.
A metadata template can be very easily created in Bridge but as Curt already stated, they don't use the same format (Lightroom as its own while Bridge uses the .xmp format)
The keyword list is easy to export and import from both applications. Export creates a text file.
In LR choose the menu metadata/ export keywords, name it properly and save it to an easy findable location (e.g. LRkeywordlist and choose desktop)
Then switch to Bridge and go to the keyword panel. Top right is little menu icon with fly out menu. In here choose import (if you want to add the list to existing list) or clear and import to replace the existing list with your new list.
In case of the latter your existing keywords will be deleted so if you need them for what ever reason again you first have to export the existing list for back up
Europe, Middle East and Africa