Well - I am no linguist, but I think the following would be appropriate:
Playing Now!Choose 'Aktuelle Wiedergabeliste' - it is not that enthusiastic
as 'playing now' but all the way better than 'Am Spielen!' which would give you bad rates in a german class for style...
Playlist'Wiedergabeliste' for the same reason and with the same restriction as above ...
Smartlistjust use this word as there is no alternative in german. All the german words that you can find for translation either have the wrong connotations or are simply too unelegant (and as a note for any language purist: 'smartlist' - afaik - is neither an english word - it is just an artificial construction in place of ' a list that helps you choose and sort in a smart way...')
Tagsame as above - if you want to use a german word (nearly no german would use a german word here anyway), pick 'Kennzeichen' or 'Markierung'. Both of them mean "attribute". The first one would be used if you would like to focus on the fact, that the attribute is a main identifier; the second one would give a connotation of 'somebody marked it, gave the attribute'. It is a hint and reference to the fact that 'attributing something' could mean 'leave ones mark', or indicating possession. (You could btw. write a whole book about the facettes and meanings of the different german words that could be used to translate 'tag').
With the other choices, I would agree...
Sorry for the long one...
Marcus