1/ double slashes are the non critical bug when fixing paths
2/ duration is shown as reported by libav, vbr files without proper tag often show it wrong (otherwise would need to scan whole file)
3/ you can have dir where you can prepare lists and just navigate there as usual and they will show as 'dirs'
4/ if you create list by ';' then look for it in ~/oscp.m3u, you can just copy it to some other name (makes preparing a bit easier as it will only contain audio files, but is not that important as list will be filtered on load anyway)
5/ you can even have http://..... stations/links in the .m3u file
6/ if you like oscp, spread the word