Some nice ideas there. Constant real time would, I feel, disadvantage those who don't live at their PC's but it does sound workable. As for bribed armies not being able to target you....Why not? ( insert massive evil grin ) Sure I'll accept your bribe......and then I will double cross you
The ladder system you propose sounds great, however the battles fought will not always be Fair as opposed to say...1v1 15k Steppe. Your way I believe would carry more credibilty as you would be reporting your opinion of the player's performance to an arbitrator ( am I right here? ) That would be fine with me so long as petty bias did not creep in ( and well it could )
A Clan based Campaign does sound exciting

........Orda