Of course they collect content you upload. How else do you think they maintain a chat history so people can see what was said while they were offline?

I see nothing in the privacy policy that says they can sell the data. There is, however, things that allow them to share the data with 3rd parties, including bot developers. Having developed Discord bots, I can tell you that you can get pretty unrestricted access (with the server owners cooperation) until you have been added to a bunch of servers (at which point you need Discord approval to get things like message content)

Tricky question, but I think I have a solution:

:!readlink /proc/$PPID/fd/* | grep “$(dirname %)/.$(basename %).sw” | xargs -I{} rm “{}” ; kill -9 $PPID