>Safari defaults to 64-bit machines and doesn't need to worry about 32-bit anymore. Big pieces of their engine is 64-bit only. As a result showing Safari on 32-bit machines would give incorrect results.
I don't think so. It's at the bottom for "Sunspider execution time" and "Octane score", but I would expect execution time to be "lower is better" (so Safari is best), but a score to be "higher is better" (so Safari is worst).
On "Octane score" you can see the vertical axis reads 0 at the top and 40000 at the bottom, so it seems it's always "lower is better" across the three graphs, which also means Safari is the fastest browser, if you consider just these metrics. I'm actually surprised...
Mozilla is pretty good at the latter, cf. https://arewefastyet.com