Yes.
If it is God, then Scripture tells us there is only one mediator between ourselves and God -- Jesus Christ.
Not a problem here. Is your problem concerning intecessory prayer that they are "dead"? Again. I think this is the question: What is the Communion of Saints? Are the Saints in heaven part of the body of Christ.
You still have not clearly answered this question. I think it is at the core of our different faiths.
You would not have a problem asking saints on earth to pray for you, but saints in heaven is a problem. So clearly, I think, this is where we disagree. yes?
(Hoping it is OK for me to jump in: :) Yes, I have a problem with intercessory prayer by the dead. First, do you have any scripture that says that the dead pray to God on our behalf? (And I'm waiting for you if you bring up Psalm 148. :) Second, do you have any scripture that says that the dead are aware of our petitions to them for prayer? I have no evidence that the dead are aware of earthly matters. Why would they be? The saved are in heaven concerned with heavenly matters, and the damned are in hell concerned with weeping and gnashing. :) You cannot tell me that the dead are "needed" to intercede on our behalf, or else you take away from God's sovereignty.
I also have a problem with our asking for prayer from the dead. You asked about the Communion of Saints and the Body of Christ, presumably to show that that if the dead are "in the club", then it should be OK to ask for prayer from one another. My answer is the same as Dr. E's, that the Communion of Saints consists of all believers, past and present. I would add that death constitutes a real physical AND spiritual separation within the Communion. Death separates the interaction between us. This is not bad, this is part of life. The physical separation is obvious, and the spiritual separation is also real and evidenced in scripture. We are commanded not to (attempt to) contact the dead. :
Deut. 18:10-12 : 10 Let no one be found among you who sacrifices his son or daughter in the fire, who practices divination or sorcery, interprets omens, engages in witchcraft, 11 or casts spells, or who is a medium or spiritist or who consults the dead. 12 Anyone who does these things is detestable to the LORD, and because of these detestable practices the LORD your God will drive out those nations before you.
Even if you say that these are all negative things, and therefore not relevant, I can say that I have seen more than one example of a Catholic interpreting something as a "sign" from a dead loved one to do this or that. It wasn't negative, but it sure was interpreting an omen. My interpretation of "consult" is just as you said before about prayer: "to ask" God tells us not to do that.