I would argue the opposite — it is immediately easier to reason about, since I see what functions are called, and I can go look up the documentations for those functions without having to go through a precompile-step.
Yes and additionally (with Chrome's DevTools) you get out-of-the-box functionality like the ability to set a break point, live edit your code right at the breakpoint, and save your change right back to the filesystem. With transpiled languages this kind of workflow is generally less streamlined -- I don't know why more people don't complain about it. The best alternatives I've seen are when people completely reengineer the workflow - I'm thinking about the Elm debugger as an example.
Thanks - I hadn't even thought about that aspect, but it's definitely a problem I would run into. As popular as React is though, I'd assume there is a browser extension or something to support the workflow.
Both of those snippets are intended to generate HTML. In that sense there's no question which one is easier to reason about/read.