I need to rename the folder that one of my projects sits in.
I have images which are linked to rather than stored in the project (this greatly speeds up the backup process).
Is there any way to edit those image links, simply changing the folder name?
For the future, is there any way to refer to an image without the full path? That is, just have the link refer to a location relative to the project folder? If not, consider adding that capability.
Changing the path of the project won’t affect the linked images, as long as the project is still saved on the same drive. Renaming a folder in the path to the image will break the link, and unfortunately there’s not currently a way to edit the links; they’d need to be removed and re-inserted. The links are embedded in the RTF files themselves, so you could try to use some tool to update these externally when the project isn’t open in Scrivener, replacing the old file path with the new one, but definitely make a backup of the project first. 
Relative links aren’t currently possible, but it is something we’re investigating for a future version. (Likewise editing the image links.)