what voltage is needed to reduce Silver (I) Oxide in alkaline medium against an inert electrode
You need to look up the standard electrode potentials of the materials involved.  While wikipedia provides an answer for $\ce{AgO}$ in acidic media, the abstract of this primary publication mentions a value of $(0.599 \pm 0.001)$ V of the $\ce{AgO / Ag2O / OH-}$ electrode, as determined against the H electrode at 25 C in KOH solution.  Note the authors find the potential dependent on the grid material their AgO-electrode was made; beside the expected-to-happen changes in function of temperature of the solution and concentration of $\ce{KOH}$ present.

A generally useful secondary literature reference for physico-chemical data you (still) may carry with you is the CRC Handbook of Chemistry and Physics by CRC Press, including tables like this, too.