On your device. There are no accounts, so it can’t move to another device. Deleting the game or clearing this site’s data in your browser deletes it.
On an iPhone or iPad the game follows the silent switch. The pause screen has switches for sound and music, and M turns both off and on again.
Yes. ← → or A D move, Space, W or ↑ jumps, Esc pauses and R starts the level again.
Privacy says what it collects, and how to have it deleted.