Thanks for the detailed notes! There is key remapping under Settings → Upgrade hotkeys, although it only covers purchase/upgrade keys right now—and it sounds like I need to make that option easier to find.
The 4× speed option is unlocked by purchasing Time Compression in the Chronicle for 3 Echoes. I’ll make the locked state and requirement much clearer. Returning to the tab should preserve your selected speed, though, so I’ll investigate that reset as a bug.