1. As explained in the Online Help at Create footnotes in InDesign: Change footnote numbering and layout , you can change the top line in Type > Document Footnote options. The Rule Above options are in the layout tab.
2. … Uh, isn't that the entire point of a footnote? Yes, the footnote moves the text out of the way, and no, you cannot "turn it off". If it does not move the text, then your note text would appear over the text at the bottom of your page. Surely that is not what you had in mind?
[If that is exactly what you want, just say so. It's just not what the footnotes in InDesign do -- or are intended to --, so we'd have to get creative and think of a feasible workaround.]