Sharing specific settings in your team

In my team we want to share only specific global settings, e.g. use spaces instead of tabs, hard wrap at XXX columns. However, all other settings should stay the same. I already found the repository share option. But this only shares all settings. The only way I can think of is to write a plugin that goes through the xml settings files and adds the requested options at the specific line. This makes it very hard to maintain though, when other options need to be added. Is there any other way to do this?

Optional: While digging through the xml settings files I discovered that only my changes are written into the files, e.g.   <option name="RIGHT_MARGIN" value="121" /> for hard wrap in repository/codestyles/Default.xml. When this is set to 120 the tag disappears. I conclude that there then must be an "ultimate" default settings file. Does anyone know where to find it?

Also: Is there a list with all available xml option names?

Thank you!