A giant on outdoor elevated, not near the rim, can make ranged or be shot by ranged?
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XXXHXXXXEEG
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H = Range attacker
G = Giant attacker
X = Clear
E = Elevated

Can H shoot G? I thought yes.
Can G shoot H? I thought yes.

What about this as well?
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XXXHXXXXOEG
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O = other standard size character
Can H shoot G? I thought yes.
Can G shoot H? I thought yes.

In all cases the answer is No. There is Elevation between both H and G therefore line of fire is blocked. From the Core Rulebook:

A line of fire between characters or squares on different elevations is blocked by:
•Blocking terrain on the same elevation as the square on the lower elevation.
•Elevated terrain of any level higher than the level of the square on the lower elevation, except the square of higher elevation the line of fire is being drawn to or from.
•Characters using the Great Size ability.

So even though the giant is ON elevated, level 2, I cannot draw lof at level 3, correct?

You can Draw line of fire as if you are 3 or 300, but there would still be elevation level 2 between both characters that would block line of fire.

If the Ranged Attacker were a Giant then the answer would be yes to all of your questions I believe. So basically a Giant on HIGHER elevation does nothing for LOF, however a Giant on LOWER elevation does a lot for LOF. Dig?