First off, we don't control the user interface, we only give pvr data to kodi, it does the displaying. You might see what you want if you change your skin.
1. Star rating: as I said, kodi had a field for this and so does wmc, so we provide it.
2. Parental rating: we provide this data to kodi too. But to be honest, I have never investigated whether the rating system wmc uses is the same as kodi, I just gave kodi what wmc had. This should probably be investigated more, but your also the first person to ask about this too.
3. Adult language, nudity. so forth - this data is available in wmc but kodi doesn't support it. You can take it up in the pvr developement forum if you are so inclined. The only thing we could do for this in swmc is append this type of data either to the program title or the description. Maybe that's not a bad idea actually, we could have an optional for turning it on.
4. Program images for the wmc guide we also send to kodi and they work for me. However in confluence they only show up current in the recordings list (at least in gotham). See this other active thread in this forum for more info:
http://forum.kodi.tv/showthread.php?tid=186486