I agree -- I think lines of code is the wrong measure. A better measure would be how large is the set of problems that occur in practice that normally would take thousands of lines which can now solve be solved with 50 lines of code using a probabilistic programming language.
I agree, but I still think the idea/algorithm/etc should be conveyed in sentences and math in the body of the paper. The code should purely be optional and not associated with the paper. I think the problem here is the author is referencing code in the paper, which puts the onus on the journal to evaluate the code. Juts put the code on your website. If people want it enough they will google you.
You can get by without math in engineering? This is news to me... I think what you meant is: you can use existing hardware and software tools to build software applications and systems without relying on "advanced" math. I would say this is the point of building hardware and software -- so other people don't need to learn how to do it. They can just "use it"
People take more risk on paper -- it's like your high school stock market contest where the winner put everything on a penny stock and got lucky. Will there be some bias like this?
Looking at fees I think you will be better off at Vanguard if you have at least 10K. You can also get Vanguard Target Retirement with 1k and expense ration of 0.18.
A single exchange brings all traders together reducing search and monitoring costs and thereby reducing trading costs. The single exchange as a monopoly can extract rents from members and has little incentive to improve stuff, e.g. infrastructure. So the tension is between the monopoly power and the liquidity externality arrising from bringing traders together to the same place. The market makers do not necessarily have a monopoly, they can compete against each other, but face monopoly level fees, potentially. (This is my amateur economic analysis, but I think basically this is what economists think.) A fragmented market increases competition on fees and infrastructure, but traders face search, monitoring costs and the cost of dealing with HFTs.