XBMC store its global configuration files, addons and skins underneath /usr/share/xbmc/ and /usr/lib/xbmc/. In addition, there are user settings stored in the .xbmc/ directory in the $HOME directory. For yaVDR, XBMC runs in the context of user vdr. Thus, these user settings are stored in /var/lib/vdr/.xbmc/. The user settings have priority over the global settings.

Overview about the most important files and directories. 

/var/lib/vdr/.xbmc/
├── addons                    # downloaded addons
├── temp                      # temporary files, log files
│   └── xbmc.log
└── userdata
    ├── addon_data            # addon settings
    ├── Database              # databases for...
    │   ├── Addons15.db       # ...addons
    │   ├── CDDB              # ...CD meta data
    │   ├── Epg7.db           # ...EPG
    │   ├── MyMusic18.db      # ...music
    │   ├── MyPrograms3.db    # ...XBMC scripts
    │   ├── MyVideos61.db     # ...videos (films, series)
    │   ├── TV20.db           # ...PVR addons
    │   └── ViewModes4.db     # ...view settings for the different modes in XBMC
    ├── keymaps
    │   └── remote.xml        # functions of the XBMC-internal key names
    ├── playlists             # playlists
    ├── advancedsettings.xml  # advanced settings (needs to be created manually)
    └── Lircmap.xml           # mapping from eventlircd to XBMC-internal key names