[Hela, Queen of Hel, collision damage]

Just for clarity and devil's advocate I'm assuming this is because you are looking at the collision of the character's to be simultaneous but i can see an interoperation that while there is no 'then' in the rules but they are two separate sentences. A Thrown character that collides with another character suffers 1 damage. The other character must make a Dodge roll (p. 18) to avoid being damaged by the Throw.

Secondly if it is simultaneous wouldn't it be the active player's choice and not the throwers to decide which to apply first for rare cases like Hero's for hire and Comrade's keeper. 

[Hood (possessed) Razor Talons vs Ronan The Accuser.]

If Possessed Hood dazes Ronan with a Razor Talons and Ronan uses the Accuser what is the final outcome?

1) Hood transforms into normal before Ronan can attack back.

2) Ronan attacks before Hood transforms into normal.

3) Ronan attacks and Hood doesn't transform into normal.  

[Root/god of mischief and Steve's leadership.]

If Antman or Wasp are under the effect of Root/God of Mischief and attempts to use an their change size or pym particle control, can they make use of Steve's leadership or since the root/GoM are a tax before using the superpower they must pay 2.