No issue with HD files whatever the size. Beside the what was prior written knowing your OS/filesystem can lead to a limitation too (e.g. FAT file system is limited in terms of biggest file on drive)
Did I mixed up 2 problems (wrong answer)? I face the same issue each time I stop the daemon for a part of my torrents, the process is no more present. Even a stop/check remaining process/reboot leads me to this.
Is the cache value adapted to your free memory on the server? Do not forget the x16
Have you installed the plugin Itconfig and selected the performance preset?
Removing the file in Deluge is followed by a popup windows asking the correct action. This one include the possibility to remove the torrents and the file.
install the plugin total traffic to monitor the amount of upload, stats is handy too. If there is no request on the torrent you have you won't upload but this way you can have an historic.