How can I rotate my images directly from the finder?
Yes - you can use Automator to make a service for Finder (or all applications) to perform rotation of images. Then you can assign a keyboard shortcut to that action.



I'm not aware of quicklook plug-in that rotate, but that's something that might exist. Modifying finder's shortcut bar might be the least likely way to activate things, but hopefully an Automator service (or app / droplet) will do.