After the first chapter, I am pretty uncertain he is Roedran, unless he has some sort of plan set in motion for when he attends the meeting.

I think he's definitely got several irons in the fire. Pretty much everything mentioned here is a possibility. One that hasn't is the introduction of alternate forces through portal stones. I've long held the belief that portal stones were used to bring shadowspawn from alternate worlds to achieve the temporary inflated numbers during the Trolloc Wars and Artur Hawkwing's reign (note that both major Trolloc invasions occurred while Ishmael was relatively free). Demandred may have recruited other forces as well; Jordan/Sanderson can get really creative. I also think we'll see some major Fifth Columnist stuff Demandred has coordinated. Like something on the scale of the finals scenes in London from The Coldest War.