To have a default file, it's in the "XML File Settings> tab", the best being to put the XML files on the network so that all colleagues use the same settings.
This option (to copy/paste a whole group) in Smartproperties does not exist to my knowledge, it is I think it is a good improvement to pass on to developers.
To do this:
from the Settings window, in a hat on the left, click on [?] then [About] and finally click on [Submit an enhancement request].
To copy only the calculation folder, you can try to save it as, then modify the XML file to have only the calculation folder, and open it in the new file, but in my opinion it will erase the old properties!