You can switch your model units through the SketchUp interface. Window > Model Info > Units. Adjust the dropdowns as desired.
You might consider creating a template… Click the File dropdown > Save as Template…
When running the ConDoc Export, the active scales are pulled from LayOut. You can adjust which scales are shown within LayOut, click the Edit dropdown > Preferences > Scales. Modify as desired, be sure to fully close and restart SketchUp and LayOut to see the changes in the ConDoc Export.
Be sure to visit the following thread to grab our Metric ConDoc resources, https://www.condoctools.com/pro-forum/topic/metric-scrapbook/.
Let me know if that helps!