Question One

Does Heat Rise or Fall?

If you put your hand above a candle then beside it that should answer it. So heat rises, right?
No, Hot air rises for he same reason ice and ships float, as well as lids pop off in microwaves.

Displacement. This is where an material like air is heated the molecules gain energy and vibrate more. The result is they begin to take up more room. Essentially making them less dense. Being less dense they rise above the denser matter and "float" up. As water freezes, becomes a crystal, the molecular alignment causes the "ice" to become less dense, takes up less room. Hence floats.

Fires in zero or very low gravity, extinguish themselves since the hotter air does not rise and the oxygen is not replaced due to lack of convection.