Hey, thanks for the feature request. The idea of letting you choose which preview a button opens makes sense, I’ll pass it to the team as feedback.
About tables: what you’re seeing isn’t a separate bug, it’s how inline Preview works. When you edit and save a document in Preview mode, the editor does round-trip serialization and normalizes the Markdown, including reformatting tables. A full preview that doesn’t change the source already exists, open it via Markdown: Open Preview or Ctrl+Shift+V, it won’t touch your markup.
A couple things that help right now:
Edit the file in Markdown mode, not Preview, and your tables will stay as-is. Each file remembers the last selected mode, so files left in Markdown mode will keep opening raw.
For viewing, use the standard preview Ctrl+Shift+V, it’s full-fidelity.