Hello Kirill,
Thank you for reaching out and I am happy to help!
1. W3 Total Cache does not auto-purge cache unless the post/article is published/updated or any other change on the website that triggers the Perofmrnace>Page Cache>Purge Policy settings.
You can entirely disable those options if you want to purge the cache manually. If the cache continues to be purged after the Purge Policy is disabled then something else might be doing this and not W3TC.
2. You can purge the single page when logged in. In the top admin bar, however over Performance and click on Purge Current Page. Alternatively you can call w3tc_flush_url( $url );
Thanks!