Limit the dock to only show up on the main display

As far as I can find, putting the Dock on the left side of the right monitor or the right side of the left monitor can't be done.

But let's look at other possible solutions to your problem. Point #1 notes that you don't want the dock on the right because it would interfere with disk icons on the desktop. And when you first drag the Dock to the right side, it does indeed cover the disk icons on the right side. But if you select "clean up" on the Desktop once the Dock is positioned on the right, it will move those icons over to make room for the Dock. This is a temporary solution, however, because newly mounted drives will still be buried by the dock. If you select "clean up by name", however, then newly mounted drives will fit into the grid created and not be covered by the Dock.

Not the solution you were looking for, I know, but it might be a workaround.

Currently there is no way to accomplish this. The Growl mailing lists have discussed allowing Growl to always place the notification on the display that you have a window focused in.

For example, you have 3 displays, oriented in a horizontal line, and you're doing some file management on the far-left display and web browsing on the far right. If Finder has focus, the notification will be shown on the far-left display, if Safari/Chrome/Firefox/$BROWSER has focus, the notification will be shown on the far-right display.

But this feature has not yet been implemented, so you are limited to explicitly configuring Growl to send notifications to a single display.

This feature has been written up on their Google Code Project page, so you can star the issue in order to receive further notifications.

Note that you can star it on an issue detail page by clicking the star outline to the left of the title "Issue 122: [...]", or at the bottom of the page just above the comment box. After clicking the star in either location, it will turn yellow and have a thicker blue outline, that means you've subscribed, and in essence, "voted" for the feature.