Reference
A chord is a key combination bound to a command, written mod+k. mod is Cmd on macOS and Ctrl elsewhere, so one binding fits both.
Nothing here is chord-only: the Command Palette runs any command by name, the Shortcuts surface lists every command with its chord and lets you rebind it, and the title-bar and status-bar controls dispatch those same commands.
mod+kmod+bmod+\mod+shift+\mod+wmod+alt+← / →alt+h j k lalt+shift+h j k lalt+aRebind any of them under Settings > Keybindings: Record a new chord, Clear to disable one, or revert to the default.
Nowhere. The console is a static page: it talks only to a daemon on 127.0.0.1, in your browser, and there is no server to send anything to. The address is checked against loopback before any request - a hostname is refused outright.
Without a daemon it reads only what rides in the link you opened: a run's output or a graph travels in the URL's fragment, which a browser never sends to a server. Nothing is uploaded, and nothing is stored beyond this browser.
Each app opens as a tab. Opening one you already have focuses its tab instead of a second copy - every surface is single-instance.
The rail down the left edge lists every app, whether or not it is open. The one you are looking at is highlighted, and an app with a tab open somewhere else is marked. Click a row to go there. It collapses to icons and back with the chevron at its foot, or mod+b.
A tab splits into panes. A split divides the focused pane in the persisted default direction (side by side, or stacked); the direction can be toggled or picked explicitly. Tap or click a pane to focus it; drag the divider to re-weight the split. A pane can also be moved into a neighboring slot without losing its place.
The Panes button in the status bar drives all of it without a keyboard.
To leave this window, right-click a tab and choose Move to new window. That is the only route to a separate OS window - opening an app never takes you out of the one you are in.