I think I'm overthinking the big spiked donut. Here's the text:

1. If Solaris attacks War Wheel at a direct-line diagonal and Wheel cannot get any part of it's base to be in the same row or column as Solaris, it cannot Retaliate, correct?

2. To "occupy the same row or column", does that mean ALL of Solaris' base must be in either the same rows or columns as Wheel, or would 1 suffice? Same question/answer should apply to any multi-base figure.

3. Assuming 1 would suffice, here's an example where Wheel was attacked, and missed, by Solaris at range. X,A,B,C are all just empty squares.

X X X X X X X
X A A B X X X
X A A B X X X
X X X X X X X
X S S X X C C
X S S X X C C
X A A B X X X
X A A B X X X
X A A B X X X
X X W W X X
X X W W X X

Can Wheel occupy any of the A-A *or* A-B squares and perform it's Retaliation?

4. Finally, can Wheel be placed in C-C and Retaliate, and the area of effect adds on a few more rows/columns?

That is a good question.

By my reading the "All of War Wheel" only applies to War Wheel and not the chosen character.

So essentially if War Wheel starts in the A-B Column he has to stay in the A-B column and can not drift into the A-A column.

I think the chosen character "Solaris" however only needs to occupy one square in the A-B column.

So

1. Correct
2. I believe 1 square of Solaris will suffice.
3. A-B only A-A is right out
4. No

I just played the War Wheel last night. Some additional information on the chart you provided. First, it's more readable if you change it to a fixed-width font by wrapping it in these tags: [FONT="Courier New"][/FONT]. (I also made it larger using [SIZE="4"][/SIZE].)

X X X X X X X
X A A B X X X
X A A B X X X
X X X X X X X
X S S X X C C
X S S X X C C
X A A B X X X
X A A B X X X
X A A B X X X
X X W W X X X
X X W W X X X

I want to point out that War Wheel's colossal retaliation trait would only lead to an attack on Solaris if you placed it in the "northern" set of A-B squares, which I have underlined above. The "southern" sets of squares (which I have italicized) do not satisfy the requirement for the attack, which is:

"Make a close combat attack whose area of effect is all characters in those rows or columns between where War Wheel began this action and the squares it currently occupies."

Essentially, the War Wheel must end up on the other side of its target from where it started in order to make the attack. This took me a few seconds to sort out when I was playing last night as well.

I think if he wanted to attack Solaris (the original attacker), that would be true. But I don't see any reason he couldn't go just about anywhere if he wanted to attack other characters, as long as he ends up in a correct location relative to Solaris.

This is indeed true.