Is it possible to upgrade to Cubase Elements 14 from the educational version of Elements 13 at the lower price, or would I have to just purchase the whole thing?
Yep…Upgrade is exactly as normal version.
Is there a possibility to update / upgrade from an education version to a higher version of the software?
Yes, but not at a special education price. Updates and upgrades can be purchased at the regular price from the Steinberg online shop. By updating / upgrading your education version, you receive a regular, commercially usable full version.