That isn’t supported at the moment. The editor manages its own scrollbar visibility, and doesn’t have a way to configure always-visible scrollbars.
Line-breaking is done by the browser, so the editor doesn’t have full control over it (and even with a monospace font, some characters that aren’t present in the font will still have a non-uniform width).
Call refresh() on the editor after it becomes visible to give it a change to lay itself out.
Look into the "beforeChange" event—that allows you to inspect and block changes before they happen.