Would it be possible for the Item Elevator to be able to connect to circuit networks and/or have filters set on its inventory slots? At present it's not possible to load it with specific quantities of items (unless I'm missing something or using it in a way it's not intended to be used).

The Item Elevator is definitely in a "band-aid solution" state. My intention is to allow both of the things you've mentioned here, as well as add the functionality of power transfer and add an upkeep cost (think Space Exploration Space Elevators), among other things ;). Good suggestion!