Nora adds an eyeball. Can Flight Insructor leverage that into an extra die?

From the wiki:

• Add: To add a die result, place an unused die displaying the result next to the rolled dice. A die added in this way is treated as a normal die for all purposes and can be modified and canceled.

Yes, you are adding a focus result, and Flight Instructor can reroll a focus result, so I see no reason why you can't reroll the added focus result.

Yes, but it's damned expensive. Consider Recon Specialist...