As you said, God has his will so our prayers whether they are for ourselves or to intercede for others are not about trying to convince God to do what we want - it's more about helping us to accept God's will for us. We have intercessory prayers to remind us that together we are part of the Body of Christ (1 Cor. 12) and that together we can do God's will.
We pray to God to remind ourselves that He is the one in charge.
Wow... a lot going on in your question. As a Protestant, you should be familiar with the idea of a prayer group. Think of intercessory prayer as a prayer group, only with the Saints, rather than with your neighbors, as part of the group.
Now, for the next question, the Saint doesn't do anything other than go before God and plead your case. You are right, no Saint has the power to perform a miracle, it the power of God that performs the miracles. Now, why should we ask others to go before God and plead our case for us?
Well why do we pay lawyers to go before an earthly Judge and Jury to plead our case for us? I mean we are all supposed to be "equal before the law", so why do we need lawyers? As for "what do they need to pray for us for?"
They don't NEED to, but they do because they want to. Generally, I would assume, Saints are nice and caring folks, generous and happy to help. That kind of thing.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.