How do I go about sharing images between two computers though?
I would like to share originals between two computers by keeping them on an external hard drive. Is this possible? Or will I have to create duplicates of the images just so each computer knows where to edit them from. It would be quite burdensome space-wise and time-wise to have copies of every image for each computer I want to use.
You don't need to share images on a local drive.....the masters are in the cloud, so if you login into the same adobe account on the two systems and install Lightroom on each, they will both automatically "see" the same cloud-based images, and have the same access to them all. You only need to import new images on one of the two systems (it doesn't matter which one, you can use both), and they'll be uploaded to the cloud and thus will be immediately accessible from the other system.
Previews of those images will be stored in the local library on each system (which is in fact a catalog, but subsevient to the master catalog in the cloud, and this local catalog cannot be moved from the system drive). You can if you want have Lightroom store a local copy of all the cloud images, but not necessary to do it on both, and there is no requirement to "share" anything locally between the two systems. The sharing is done via the cloud, so the Adobe servers handle all that.