Hey Isabella,
Nabeel answered your questions correctly but it sounds like what you’re expecting is different so it’s not accurate to you which is understandable. Let me clarify or connect your questions to Nabeel’s answers then add my own reply to attempt to make the overall answers accurate.
My answer: Yes. The page will display fine since the builder’s shortcodes are already generated. But, if you edit the page using Gutenberg, you won’t be able to go back to Cornerstone builder without losing the edits you’ve made in Gutenberg. You can try it.
My answer: No, because Cornerstone is required by X. They share functions. What you can do is disable Cornerstone for all Post Types in X > Settings > Permissions
------------------------------------------------------------
To your new questions:
Almost all the Classic Elements have a shortcode version but we do not recommend that use of them anymore as coding is error-prone. If you still wish to use them, you can check the old demos here: https://demo.theme.co/integrity-1/shortcodes/
V2 elements don’t have a shortcode version but if you wish to display a V2 element using a shortcode, you need to create a Global Block. See https://theme.co/docs/global-blocks
Hope that helps.