5. MOST importantly, I have a proposal that to every newbie, there should be a warning "Do Not Copy/Paste other people’s work without Citing". This warning will remain at the top of the newbies page immediately after the menu bar. Maybe until the newbie will become a Jr member before it can be removed.
Many good ideas have been proposed already, including welcome messages of various forms, but nothing is happening on that front.
I think KingDen's idea is a pretty good one myself, and suchmoon suggested something very similar recently:
If a simple sentence was added to the "Post reply" / "Start new topic" page next to the "Post" button, e.g. "don't make low value unnecessary posts and make sure to add links/quotes if you copied text written by someone else", I think that would significantly help users who don't really intend to plagiarize, but perhaps don't know (cultural differences and whatnot) that unreferenced copypasta is not cool, or forget to format it properly.
If either suggestion were implemented, newbies would have absolutely no excuse and no grounds for appeal if they posted someone else's words without crediting them. And given that the problem is extensive and has been going on for so long and that it would probably be an easy thing to do, why not do it? Seriously, how much coding would Theymos or whoever have to do to insert a warning like that?