Chess Clock

Increment adds time after each move and can push your clock above its starting time. Delay only protects the opening seconds of a move and is lost if unused, so your remaining time never grows.

You lose on time. Under FIDE rules it is a draw instead when your opponent cannot possibly checkmate you by any legal series of moves.

Yes. Once the page has loaded it keeps timing without a connection, and it holds the screen awake where the browser permits it.