Yes — heading levels in the ODT convert to the matching number of `#` characters, and bulleted / numbered / nested lists convert to `-` and `1.` markers with correct indentation. The MD preserves the document outline so the structure is immediately readable as plain text.
Yes — the output is GitHub-Flavored Markdown, so it renders correctly as a README, wiki page, issue, or PR description on GitHub and GitLab. Pipe tables, task lists, fenced code blocks, and `#` headings all display as intended once you paste or commit the MD.