I think you'd use nei (neas/neis/neos) for that - verbs in constructed languages don't usually have several meanings (at least at first) as in natural languages where those alternative meanings sprung from common use (krokodili is a good example of a verb formed through common use by Esperantists).
You use it for closed questions.
Open questions, you just turn the part you don't know into "who/what/when/where/why/how" and make the question:
You hid (something).
You hid what?
What did you hide?
Kion vi kaŝis?
Closed questions, you add ĉu to turn it into a question:
You want X or Y.
You want X or Y?
Do you want X or Y?
Ĉu vi volas X aŭ Y?