Rather more than that. But I doubt it would be AC in a solid state design.
You're thinking more of valve gear. Transistor stuff like this usually just has one transformer winding. It dates from before the days of split rail stuff being common.
Yes. You could go for a higher voltage and nominal current - if not too far out will only effect the colour and likely intensity of the lamp which probably doesn't matter too much if just an indicator lamp. If one of a pair etc for dial illumination best to replace them both so at least they match.