Note on #3, that's not what you want to do. In fact, that's a REALLY BAD IDEA as you're deleting the trash itself. Often when you do that, you can no longer move anything to the trash, because the trash folder itself doesn't exist.
I would open a terminal window and type this:
cd ~/.Trash
(note if that doesn't work, you have a problem as you don't HAVE a trash).
rm -rf ./*
YOU NEED TO PASTE THAT OR TYPE IT EXTREMELY CAREFULLY. It will delete everything in the current folder, which will be the .Trash folder if the previous command completed.
You can try sudo rm -rf ./* as well from the same folder, subject to the same precautions.
Also note: If you have stubborn files, it may be because a process is hanging onto them. I'd actually suggest rebooting first, and then trying to just empty the trash.
If you don't have a ~/.Trash folder, you can recreate it, but it may not have the right permissions and you may have long term problems with deleting stuff properly because of this. I'm not sure of the exact permission you need on the Trash folder for this to work properly.