Evolution is a side note to the Christian life. It is not primary, and it ought not to be a distraction.
Honesty, though, is central to growing in Christ, and honesty is always what I'm after. We may be human and prone to biases and misconceptions, but there is still a difference between those that follow the evidence and those that only gather evidence to bolster their own position.
So here's my answer to 1.) a biblical argument, 2.) a speculative, almost philosophical argument, and 3.) a pseudo-scientific argument. On the scientific one, I am attempting to keep the argument on what matters. Most scientific arguments against evolution are inaccurate, but the ones that are accurate are usually irrelevant.
Introduction: On Evolution and Following Christ
First, it's important to me that you know that I am first and foremost a follower of Christ. I address the evolution issue because it is prone to making people stumble. There are people who see all the scientific evidence for evolution, and it makes them question their faith. I am trying to help them not to stumble or question. A faith based in a powerful, real relationship with Christ will not be shaken by evidence for or against evolution.
That's the issue that matters to me. If evolution turns out not to be true, that wouldn't bother me a bit. I believe God is involved with creation from front to finish whether it happened by evolution or whether it happened instantly through a command of God.
That said, it appears unquestionable to me that the evidence for evolution is very strong, and Christians are failing miserably at finding good arguments against it. That's no problem to me, since I don't think we have to bother coming up with arguments against it. Even if evolution is true, God is still Creator, Jesus is still Lord, and the Gospel still transforms those who embrace it.
Okay, to your questions and arguments ...
1. There are many definitions for "firmament."
I don't believe that's true. I think that the concept of a firmament being something solid is basic to the word, and we just refuse to admit it because we don't like it. I consider the word "expanse" to simply be a dishonest translation, not one of many options.
I don't think the research into that word is that hard. And even if we avoid admitting that firmament is something solid, then we still have to contend with Job 37:18, which specifically says the sky is hard and hammered out flat like metal.
2. The earth only looks like it evolved, though created recently.
Why would God make the world to look like it evolved? I can understand the appearance of age. It takes time for light to get from distant stars to us, so if he created the universe 6,000 years ago, it would be good to have the light already made so we can see the stars.
But really, do we want to believe about God that he created the world to look like it evolved when it didn't? Why would he do that? And why would he tell us to pay attention to his creation in order to learn about him (Rom. 1:20; Ps. 19:1-4) if the creation is tricking us?
3. Inbreeding Depression
It is much harder to prove that something is impossible than to prove that it is possible. Even many scientists used to believe that it was impossible for a human to run a 4-minute mile. Obviously, it's not; it's been done.
We all know that inbreeding causes problems with DNA. So how could life have evolved from just one original life form?
The correct answer to that question is that it's irrelevant.
There is lot's of evidence that life evolved. For example, one of the strongest pieces of evidence is that the same sorts of fossils are in the same layers of the earth the world around. Where you find dinosaurs, you don't find horses or humans. Where you find ancient amphibians, you don't find any reptiles or mammals at all. Where you find "Cambrian Explosion" fossils, you don't find any vertebrates at all--no fish, reptiles, amphibians, mammals or birds.
There's a progression in the earth, and when you conclude from that progression that life evolved, then thousands of other pieces of evidence fall into place.
Thus, somehow, evolution happened despite the problems that inbreeding can cause.
Of course, there's also a good explanation. The earliest life didn't reproduce sexually. Those cells simply copied themselves, so there was no inbreeding. Later, it's whole populations that evolve, not one or two individuals.
Even in a lab, you can isolate two populations of bacteria--or even two populations of moths. Let them reproduce through a thousand generations, and changes happen. Not the same changes in both populations. At the end of those thousand or thousands of generations--which can be seen in a lab due to rapid rates of reproduction in insects--and the two populations are different enough that they won't breed together anymore.
Nature has conducted such experiments throughout earth's history. Populations get large enough to spread over a large geographic area, and sheer size sometimes separates them into groups. Other times, they're on two sides of a mountain with different climate on either side. Or one ends up in the forest and one out. Or they spread across a group of islands. Etc., etc., etc.
Please understand, these questions have been asked. Science was not started by atheists trying to disprove God. Most early scientists were Christians. Evolution is the result of looking at the earth, not the product of people hoping that life evolved.
The people who first suggested evolution had to face intense scrutiny, and questions like the ones you're asking have been asked over and over again. Answers have come pretty easily, which is just further evidence that life evolved.
Charles Darwin's On the Origin of Species
Even Darwin's original On the Origin of Species was full of arguments he had received against his theory of "descent with modification." His answers are amazing and full of natural examples. You can learn a lot about nature from his book, and most of it is fascinating. It's sad more people don't read it. He wrote the book as a believer in God--though he had his doubts--so it is not an attack on people's faith. He had a wife he dearly loved who was a Christian.