If we assumed that he created other animals in similar fashion what would geneticists expect to be different in their code than if they evolved?
A few people have mentioned Junk DNA and redundant features and vestigial traits and the like. That is one good answer to your question and it has been covered well so I will not cover it further other than to say that if you assume a designer made all the animals together then these are things that require a lot of explaining.
Another difference I have not seen mentioned however is that genetics show all the hall marks of the historicity of evolution which one would not expect if they had been all created at the same time.
What I mean by this is easy to explain but probably harder to understand. Imagine for a moment ignoring genetics entirely. Instead you use all the other methods at your disposal.... for example dating techniques and fossils etc.... to "line up" all the animals in the world today on a family tree and draw up where their common ancestors were on that tree as far back as you can.
If you THEN and only then look at the genetic make up of the animals on that tree you find it lines up perfectly. There are methods for dating Genes too and we find that the points where genes arose and diverged in the gene pool match where we thought common ancestors diverged on the ancestor tree.
This is either massive evidence for the truth of evolution of course, or the scientists engaged in such practices are suffering from an abundence of sheer luck comparable with winning their local state lottery many times over. In a row. The predictive power used to test Evolution has consistently been so strong in fact that I am still constantly agog that there is any doubt of its veracity.
I would certainly recommend the Ancestors Tale as a good, if long, book about just how this genetic historical tracing works and how it has been applied in Evolutionary Theory.
So bacteria was the first organism?
Not quite, and it is a very difficult question to answer. Like much of evolution it is quite like asking about a rainbow where red ends and orange begins. One can not point to a single point on a rainbow and say "This is the first bit of orange".
Similarly the first rise of life was not bacteria. It would have simply been a protein that was capable of replicating itself, or if you want to get technical about it a protein that was able to act as a catalyst on itself in reactions that produced more of itself.
This would have been the first rise of "life" on the planet and as soon as a self replicating series started then "Evolution" could kick in. The proteins would have replicated in different ways, then had different results, these results would each have reacted on each other producing new results and combinations and so on. Out of this would have eventually risen things like the Cell and more which would lead to what you know as Bacteria.