If I have a soaring figure adjacent to my Sentinel and somebody EEs him, does the soaring figure take splash?

Wow.
That's a good one. You know, I don't think that he does! While the Sentinel can be hit, the soaring figure is still fine, unless maybe he's in the "halfway" range. I'm not sure, so don't bet on it until we see Psylockeslover or someone else.

This would be a great one to send to Wizkids to put in the next FAQ.

To clarify: The figure EEing the Sentinel is ground level and to far away to strike the soaring figure.

Right, but, the Sentinal is also considered adjacent to the soaring figure

I say soaring characters take the damage, cause sentinels are adjencent for soaring characters also. Not sure.

But here is easier question. If I shoot Sentinel with EE are all 12 squares having splash damage? If so I don't like it and they should change it to 5 (I know they won't).

All 12 squares around the Sentinel are adjacent so 12 characters could potentiall be hit by splash damage.

As for splashing the soaring figure, I don't know if the new rules confirm that a soaring character is considered adjacent but I would say that with them being able to do close combat attacks on one another that they should be considered adjacent.