just a suggestion to increase your numbers of mounted staff officers, adc's, couriers etc, you should have spare cavalry figures why not use these by trimming off unwanted details and painting as appropriate, prussian mounted officers in caps can be painted up as russians(in metal again Hinton hunt), a few head/body swops from infantry figures should supply infantry commanders etc. As to metal makers Newline Design produce Russian mounted generals, hope this helps
cheers old john
The Italeri French staff set has some figures which are fairly easy to turn into Russians. Cavalry generals were usually in some sort of regimental outfit, and Art Miniaturen Prussians, particularly the ones in overcoats, can also be turned into Russians with a fairly simple paintjob.
Hope you'll post some pictures when it's all done!