Let's talk about the difference between an Importer and the Interface for importing.
In comparison with the Importer the Interface has an internal inventory to receive items and import them (through piping, hoppers, etc). That internal inventory is accessable by opening the GUI and looking at the slots under "Interface Import").
The Interface does NOT suck items from adjacent inventories automatically, you have to actually insert them in the Interface through piping, hoppers, etc.
There is also an option for exporting items from the system. These items can be piped out through a piping system from another mod, hoppers, etc.
It can be configured to be NBT, damage and oredict sensitive.
To clear an exported item configuration use SHIFT and click on the item to clear. Use the left and right mouse buttons to increment or decrement the amount that has to be exported.
In Minecraft 1.12
If no export items are set, the entire RS storage inventory will be made available as a regular inventory for extracting with pipes etc.