Can you still download Yosemite? If not can I clean install Yosemite from a USB stick made for another machine?
You should be able to download Yosemite from the App store if you login with an account that had previously acquired it.

If the USB stick was made with an App store copy of "Install OS X Yosemite.app", it will work on any hardware that existed prior to the release of the copy you downloaded.