Can't imagine anyone who isn't fairly new to Tiberian Sun (and modding it) will take more than 2 seconds of thinking to realize the answer to any of those questions; especially those who have either played or modded TS for over 10 years... Which would be most of the people here

I'd suggest you use trickier questions to which the answer was only mentioned a few times or even just once during either the missions (that includes the briefings, mission descriptions and videos) or for which the answer wasn't even mentioned in the game at all (make sure you have the source to back the answer up then however).
For example "who crashed the Scrinship?", "when was it built?", "what do mutants call uninfected humans?", "where did Kane get the Tacitus?" and so on...