From what I've read (The Orthodox Church by Metropolitan Kallistos), 1). prayer to the Saints is effective 2). The theology of the body is not a "ghost in the machine" but that one's soul is bound to the body until the Resurrection. So how do they intercede for us?
I don't know if "bound to the body" necessarily means "trapped in the body." We have a prayer for separation of the soul from the body, used by the priest in cases of great suffering near the end of life, to pray for a peaceful passing. Their separation doesn't imply complete independence, insofar as they will be reunited in the Resurrection of all; but their tie to one another doesn't imply an inability to separate, even if only "temporarily" upon death.
If you then proceed with the idea that soul and body can be separate between death and the Resurrection of all, then the issue of the intercession of the Saints is much easier, no?