So ... here is the deal:
in the Generals Tournament, every type of General, but the Defence General has the option know exactly what their special thing does. In the same time, defenders rely on expeditions for profit, but no clear info can be found on expeditions. The two variables on that are numer of expeditions per level and recourse that is gathered (although the resource might be a constant). I think it's fair that those numbers get somehow put in the description of either the research or the ship. I think that this would only be fair ...

And if Voyagers ever fail. Do they?

nope, each time voayagers bring ress back