Hi there,
I've done programming and I've had some biology in college hopefully my response is helpful.
1. DNA is the genetic material. It's the only thing that gets transferred from generation to generation. So yes if you connect the right nucleotides (base pairs) that encodes an organism you want together and stick it into an empty nucleus in an egg of another. You would get the one you intended.
2. This is the question most people have about evolution and most difficult for them to grasp. How can something so complex arise out of random mutation and selection? Well, 4 billion years worth is a start. The earliest organisms we've found are microbes and they are 4 billion years old. Back to the question....How evolution works is that organisms adapt to their present environment. They can't anticipate what they need 1 million years later and start evolving to that form. In your example of a computer program, you wrote it in perfect form to be able to work in its present environment. Now suppose, the environment changes. Say... your compiler gets buggy. It no longer translates some command to its appropriate assembly code. But lets say you compile your program with another program called "natsel.exe" that can detect where your program failed. "natsel" will randomly replace the bug with alternate commands until it finds one that works with the compiler. Most the replacements will not work, but eventually one will work.
What i'm try to get at is that you have to look at the organism within context of its environment though its history. What its form is today is the form it needs to survive in today's environment. Organisms are always changing(because they have to cope with the changing environment) so you can't compare them to a car or a finished product. So you cannot say what if I took away this part here how can it survive. Organism don't change that fast as you can see.
It's getting too late maybe i'll finish tomorrow.
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