Set your allow and disallow paths per bot and your sitemap URL, and the tool assembles a robots.txt with the matching User-agent blocks.
Disallow in robots.txt only stops crawling — a previously indexed page can still appear in search results. Use a noindex meta tag to remove it from the index.
Yes, as a starting point — double-check paths, URLs, and directives against your actual domain before deploying.
No. Everything is built client-side in your browser from the values you enter.