sorry, probably a dumb question, but photo 16 of 'base kit' shows a set of number keycaps. every other photo shows this keyboard as not having that option. are those just supplied if I want to use a different case?
Every other photo are just examples of what the set looks like on a keyboard. The base set photo tells you what keys you are getting. This comes with a numpad kit included in the base.
Photos 15, 16, and 17 are all the keycaps that will be included for those sets if you ordered them. You get lots of extras so that it could accommodate a wide variety of keyboard layout and sizes. The other images are just renders of the keycaps on the more common keyboard layouts. If you have a full size keyboard, the set should be able fill them up (just make sure function keycap sizes like the shift or ctrl/alt fits your board specs).
The metal artisans from the original buy unfortunately did not work out (quality issues with the manufacturer). There are no plans at this time to find an alternative means.