Those were the same objections I had before I embraced on classical theology. After reading Ed Feser's 'Aquinas' and subsequent study, I was able to better grasp these concepts. Having participated in forums on these debates with people much more qualified than myself, it became clear that nearly all the objections are from distortions and misunderstanding of the actual argument. Feser has a blog where he unpacks this stuff regularly.
In the sense of the objection and how you are using do and act, yes. Actus Purus has a lot detailed info, and based on what you've referenced, I should think it would be available to you. There is no change in God and God is not contingent.
That being, there wasn't a time where God was deciding, create or not to create. This is all consistent with DS. Is it 'simple', no, it's a very complex subject.
What you are suggesting is that it makes God impotent. This is because you see this as an inability, or a lack. To put it simply, if God cannot chose between a and ~a then there must be some deficiency or lack. There is a ton written on the subject and as you probably know, it can get crazy technical in the terminology.
