Why is my footnote "glued" to the text?

I think you might also be interested in the package footmisc.

When you use \usepackage[bottom]{footmisc}, it always puts the footnote as much to the bottom as possible.That means that if your page breaks for whatever reasons (preventing widows or orphans), e.g., 3 lines before it would be full, the footnote is typeset to the bottom as if the page was really full.

The result is you have all the footnotes on all pages at the bottom.

You're telling TeX that breaking a page in the middle of paragraphs is infinitely bad. As a result, it's starting a new page after the first paragraph which results in a really underfull page. If you want the page to break after the first paragraph, you should write \newpage after it.

I think \interlinepenalty=10000 is absurd. If you want to control paragraph breaks to that degree, you should simply be explicitly laying out each page.