Mounted Combat Questions

So I was playing around with mounted combat and I noticed a few oddities (perhaps intentional ones):

1) High Ground from a mounted target seems to work even if your base isn't 2" higher?

1a) Presumably if the opponent had a base they would also get High Ground (effectively giving both sides High Ground 1).

1b) There aren't any listed restrictions on when this can apply. Does this mean you get High Ground shooting at non-mounted targets?

1c) High Ground can usually be used if you go offense or defense, though the use of "targets" implies it only works while you're attack. Does mounted High Ground offer you a bonus if you go defensive for ranged and melee?

2) Does Mounted Combat stack with this? I'm pretty sure it does and can be used anytime High Ground can.

3) Do you need the Mounted Charge trait to perform a Mounted Charge? It's not listed as a trait for the common mount, but it's described as being a benefit of being mounted in the Core rules.