That's discoverable by holding down Option while the Edit menu is open. This pattern of "revealing" additional functions with modifiers in menus has existed on macOS for a very long time.

> Speaking of pressing [enter] on files, that should open them, not rename them.

> For that matter, pressing [delete] should delete files. You just have to know that the key for that is [cmd+delete], and that deleting things is called moving them to the trash.

Adding a modifier to these functions helps prevent accidental irritating (opening 500 selected files) or potentially destructive (moving selected files to the trash) actions due to fat fingering, which is a particularly likely occurrence on laptops where edge keys like delete and return are easy to accidentally hit just moving around one's laptop. The accidental opening by hitting return one is something I've done several times over the years and it's never not infuriating.

On Windows, deleting it moves it to the Recycle Bin which is functionally equivalent to what macOS does. In fact off the top of my head I don't know of a modern desktop environment that just directly deletes files without recourse.

> It's not clear to me why I can't close Finder by pressing [cmd+q]. Quitting finder is usually all I want to do when it's open.

Because the Finder powers the desktop too and its windows are not separate processes. In fact no application on macOS spawns additional windows as separate processes, that's a Windows/Linux thing.