Ok I'll clear up the questions asked...
They may only keep the power of the first race they attack... Not EVERY race they attack.
They keep the power for the whole game.
If they attack the snowflakes they have the snowflakes power.
Their power is activated when THEY attack someone.
Not when someone attacks them.
The snowflakes power is activated when they attack someone else not when someone attacks them (correct?)
Hope that clears it up..