Speed: that's the same scale as characters.  100 is human norm; higher is faster.

How it works, to the best of my knowledge: every turn you get your speed in "move points", which you then spend on Doing Stuff.  Moving costs the terrain's value, melee attacks cost a value based on the weapon's weight, etc.  If you see "moves -= XXX" in code, that means that whatever just happened takes that many move points.  If your move points go negative, you effectively lose your turn(s) until you've regenerated out of negative.