Which preposition is more proper, when saying "publish a paper (in, on, ...) a conference, proceedings, or journal"?
It's been ten years since I published a paper anywhere, so I hope people more currently involved in academics will also weigh in. I would say any of the following, and this list is not intended to be comprehensive:
Conference vs. Proceedings
I would normally consider "the conference" to be the meeting you attend to hear talks, panel discussions, etc. I would consider "the proceedings" to be the publication that you receive at the conference that contains the published papers.
People sometimes say the following, and I understand them when they do:
Personally, I avoid using that construction, since I wasn't the one who actually published the paper -- the journal published the paper.