1. The above unquestionably firstly declares determinism.
I'm only going to address this one point because the totality of your post flows from a wrong understanding of this point.
Here, again, is Westminster:
God from all eternity, did, by the most wise and holy counsel of His own will, freely, and unchangeably ordain whatsoever comes to pass; yet so, as thereby neither is God the author of sin, nor is violence offered to the will of the creatures; nor is the liberty or contingency of second causes taken away, but rather established.
The first clause is not talking about "determinism," as you presuppose. The first cause is addressing what we refer to as Sovereignty.
To say that God is sovereign means that He does as He pleases. Where you err is that you presuppose that this means that He is controlling persons like pawns, bishops, knights, etc. on a chess board. But, we, and the Westminster Divines, did not believe this.
If you look at the second clause, you will see the use of the adversative conjunction "yet." This means that the second clause and the first clause do not exist in separate vacuums. Rather, due to the use of the adversative "yet" it is understood that God ordains all things or God is sovereign over all things but that sovereignty does not make Him the author of sin.
If you further not the third and fourth clauses, they begin with the coordinating conjunction "nor." The "nor" looks back to the "yet" and continues the exceptions, extending the exceptions to to say that God does not over-rule the will of the creature nor does He remove liberty.
Now, it is obvious that you disagree with Westminster. That's fine. But, it is really absurd to try to redefine what is so clearly written based on your presuppositions. In other words, you need to let Westminster speak for itself. Once you have done that, you are--obviously--free to confront the ideas contained therein. For example, you can say "The authors of Westminster say that God ordains everything that comes to pass and they say that God isn't the author of sin. How can those two ideas be the case?" In asking questions like this you argue the merits of the confession itself rather than setting up a strawman and holding the arguments of others to your strawman born of your own flawed presupposition drawn from an unfair reading of Westminster.
Also, it is important to remember that the Confessions themselves are just that--confessions. Often they do not give reasons. You are looking for reasons, and that's fine. Don't look for reasons by redefining the confession. Take the confession at face value and then ask your questions.
The Archangel