Quick question...does the ambush mechanic (specifically from hiding) factor in height of your opponent to determine whether one is successful or not in hitting a target? Do 'little people' need not aim for eyes and so forth?

There are two effects at work. The already mentioned inability to hit the top part of taller critters, but large characters also take quite substantial penalties to aiming when attacking small critters.

Little people can't reach the eyes of standing big critters but can poke them quite effectively after legging the critter. Big people can try to poke the eyes on little critters, but until they have levelled enough to build up a lot of aiming skill, they will frequently miss.