Some SPAs and other sites have useful right click actions that I want to preserve. Does this setting disable those?

(For the pasting, I agree with you. I can't think of a single reason I'd want a website to prevent me from pasting)

You do not end up losing those. Both the popup menus - the site's as well as the browser's - are shown, the latter on top of the former. Press Esc to make your browser's vanish, and you still have the site's available.

Thanks. I just toggled both of those settings.

I thought some complex web app (editor like) supports copying and pasting complex non-text structure.