If you require some information you can say:
Could you tell me if/when/how much/why...?
I wonder if you could tell me...?
I'd like to know...
I'd like some information about...
If someone asks you for information you can reply:
As far as i know...
Well,(in confidence,) i can tell you that...
I'm afraid i don't know...
I've no idea,I'm afraid...
I don't have that information available just now,can i call you back?
I'm not sure,I'll have to find out,Can i let you know tomorrow?
I'm afraid i can't tell you that,it's confidentail.