My favorite analogy is email- it doesn’t matter if you have @gmail, @outlook, or even disgusting ones like @yahoo or @hotmail, you can send and receive emails using the same protocols between any of them.

No, they’re a lot bigger (although some are partially buried) - spoilers for Depths locations and items in this link

No,

Some kind of disturbance, not really sure. I was focusing on the serene beauty 🤷

There is a text box just under the post with a "Post" button, at least for me: