Hi Chris
OK think I understand now :)
The Primary always needs to be completed.
demo1 can also be the same as the Primary (so that the Cart/Checkout image has some image in the Product page that keeps the whole thing tied together visually) - up to you whether you set the demo1 as being a Primary image or not.
demo 2 will not be a Primary (or Secondary image) and thereofre you will be able to put its own url in under the Product section (Edit Image Properties), and follow for any other images (demo3, demo4, ....)
In the Chunk 'ProductTemplate (which is what your product should be defaulting to to use) you will see that there is already a reference to the IMAGE chunk. You can create a new chunk reference for each image or one for a group - up to you in how you want to format/structure your HTML.
You will need to edit the chunk IMAGE and create a new chunk (or chunks) if you have added in the 'ProductTemplate' (eg. IMAGE2).
The IMAGE chunk(s) need to have the end parameter matching the name of the image your calling
eg. for demo1
[[kiwee? &elem=IMAGE&img_name=demo1]]
eg. for demo2
[[kiwee? &elem=IMAGE&img_name=demo2]]
Hope this helps.
Richard