WP Smart Editor

Yes and that's really easy!

JU Translation is a translation tool included in all our WordPress plugins: get, share and manage your extensions translations from a visual and easy to use interface! More information here:
https://www.joomunited.com/news/ju-translation-translate-and-get-extension-translation

The plugin have a really small impact on page load, only few additional Kb are added on admin side of your Wordpress website.

Yes it is, it has been tested with a lot of plugins and themes on the market furthermore it's a natural extension of the WordPress default editor.

So it can be used in WooCommerce, page builders, admin and frontend.