This is one of the great things about the *arrs. They will create a hardlink to the file in your media folder structure so that you can keep seeding and have a well organized/named media library without wasting storage.

Prior to that, I also just saved my torrents directly to my media library, and used the torrent manager to rename the local file properly. Same thing effectively, just a lil more work.

As the other comment says, use hardlinks and then you can have several copies of the file across the same partition all reference the same file, using just the storage space needed for one copy of the file. Still RAR files will need to be extracted first, so those would require just about twice the file size, but hopefully people stop using rar, so that's not a concern.

No.
Seedboxes just arent (usually) used as streaming servers.
So we fetch the downloads from the server and purge unpopular/non-important torrents

Here's a tip: after moving the folder (idk if this counts after renaming a folder or file, probably doesn't), go into your torrent client and click Force Recheck on the torrent. it'll recheck everything and continue seeding the file.