6.63.3 Can you answer these questions?

6.63.3.1 How to Reposition the Footnote Mark?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=569962

I often use the \footnote command and most of the time, I am satisfied where the footnote mark and adjoined footnote appears at the bottom of the page. 
However, there are times when I would like to ... 
[footnotes]
 

asked by I. Chekhov https://tex.stackexchange.com/landing/r/digest?cta=user&id=227224 1 vote

6.63.3.2 Extra blank line before heading not immediately preceded by another heading

https://tex.stackexchange.com/landing/r/digest?cta=question&id=569594

What I would like to obtain is an extra blank line before a heading if this heading is not immediately preceded by another heading. This is what I have so far: 
\setuplayout[grid=yes] 
\showgrid 
\... 
[context] [grid-typesetting]
                                                                                  

                                                                                  
 

asked by Oliver https://tex.stackexchange.com/landing/r/digest?cta=user&id=228278 1 vote

6.63.3.3 Tikz with equation regions

https://tex.stackexchange.com/landing/r/digest?cta=question&id=569683

I'd like to plot in tikz the below constraint on the unit cube defined by the region x, y, z in [-1, 1]. 
x^2 + y^2 + z^2 - 2 * x * y * z <= 1 
I found Making a 3D colored pyramid in tikz though it ... 
[tikz-pgf]
 

asked by sean1860 https://tex.stackexchange.com/landing/r/digest?cta=user&id=228334 1 vote