So Veers has "->Spotter 2" and Electrobinoculars, the equipped unit gains "->Spotter 1". Does Veers gain Spotter 3 OR does he gain two instances of "->Spotter X"? I ask because as Spotter is a keyword and keywords stack, however as as each is an Action for the Veers and actions do not stack.

Correct - and you can only take the same action once per activation (except a move). You’d get spotter 3