The earliest moments of the Big Bang are speculative, a lot of it is theoretical. The Big Bang is also part of what happens "in the universe" being that it is a description of events, not any sort of initial force or cause.
That's true - it would be more accurate to say that the singularity is potentially the first cause. As for being theoretical, when it comes to this subject everything is theoretical.
I'm not sure how all of that follows.
It is not necessary that God be omnipotent to fit the definitions given in Aquinas' arguments. Anything capable of creating a universe would work.
Language and philosophy require the use of abstracts. Anything that cannot be directly observed is either in the mind, or abstract.
All of which need to be clearly defined in a good logical arguments. That's why there's no room for nuance - understanding logical arguments shouldn't be a matter of interpretation.
The Big Bang is a description of the initial events within time. There is no explanation of how time and space exist. In fact, the universal laws must be assumed for the Big Bang to work.
Not really. It is still unknown exactly what happened in the first few moments, because the laws of physics break down as you go further and further back.
Now, because the universe is finite, and current observation makes a closed universe very unlikely, it is not reasonable to assume an infinite chain of causes. Therefor, we arrive at the necessity of an initial cause.
The universe is a closed system, but why does that mean that it cannot be part of a larger system?
Wikipedia: Perfection is, broadly, a state of completeness and flawlessness.
Perfection, completeness, and flawlessness are abstracts. As such, they encompasses different traits depending on the object they describe. In the sense of a perfect God, this requires a completeness and flawlessness which transcends subjectivity.
Why? Our language (poorly) explains the universe, it does not bend reality to fit it. Just because the word perfection may demand objectivity, it does not make it so. Where can we find this objective standard of perfection, as to be able to judge God by this criteria, it must be a separate entity?
What Aquinas referred to as perfection in the world/universe is akin to the idea of the Fine-tuned Universe.
The fine-tuned universe argument is weak as well, as it relies upon a sample size of 1. We have one universe to judge, and it works for life - we do not know how many failed universes there are, or were, or will be.
Your summary of the 4th proof went from "I want it to be so it is true" to "there is a balance, therefore God exists" to which I argued that we don't really see a balance. A balance should be expected of a universe without direction. What can be observed is an upward trend of progress; things build up, increase, and improve more often than break down, decrease, and decline. While we do see the latter, providing the universal possibility of balance, the overall sum is not balance, but growth.
What about entropy? Besides, and I'm not saying this from a knowledgeable position, but the total energy of the universe is apparently 0. This seems to explain it (in a rather complicated fashion):
http://www.iigss.net/Scientific-Inquiry/June07/2-Fiscaletti.pdf
I think we'd find that suicidal individuals believe life to be not good only temporarily. If a murderer believes life is not good and therefor kills, should he be left to his subjective view of life's goodness? Or would we agree that his view is skewed? Objectivity is what exists beyond the moment and beyond the self. A single moment to the contrary of a universal truth does not simply dismantle it.
Some suicidal people will forever be suicidal or depressed. Your example of the murderer shows that subjective views exist - if there is an objective truth to compare them too, where is it? What is it? And how do you know it exists?
I don't know about many, I expect people who think any of these are good things are relatively few. Would you honestly state that slavery, dictatorships, and downtrodden classes should be allowed to exist, regardless of whatever power to change these circumstances? Should genocide be allowed only because the killers believe it is right?
Now we're heading in the direction of morality, which is an entirely different discussion (but definitely an interesting one) that should probably be had in another thread.
However, I will point out that slavery has existed for a very long time. The Bible takes no issue with slavery, or the existence of inequality. Belief systems and worldviews around the world have a concept of a class system - feudalism, for example, which most of the world has followed in one way or another.
It is my view that, as right and wrong exist within the human mind, the existence of different opinions demonstrates that they are subjective. If there is an objective criteria, it must exist somewhere else, but we have not found any suggestion of it anywhere.
Even if the outcome of a random mutation is predictable, the mechanism itself remains random. Allowing for an infinite possibility of variables, it's as likely that evolution would have produced a stalemate of equally fit species. Of course, evolution is not the only factor at play in survival, but environmental advantages and disadvantages provide a greater possibility of relative stalemate between species. If some aspect of evolution somehow counters this, I'd like to know about it.
The environment and survival are part of evolution. What you're thinking of is mutations, which are essentially the first step. Those are random up to a point - there are still limitations on what is possible - but it then moves on to survival of the fittest, which is not random at all. Ecosystems generally do find a balance, but environments change, and the balance is destroyed. You only have to look at human action to see how this happens.
Again, though, this is heading into new thread territory.