Just looking at the FAQ:
1) I used to play Cull the Weak on Fledgling Chaos Spawn to activate their effect but the FAQ says sacrifice is not the same as destroy, so I guess this combination no longer works?
2) Do Forced effects open up an action window? After my Sadistic Mutation does damage to a Lobber Crew, could my opponent sacrifice the latter for its Action? I think no because the original rulebook lists 4 card effects: Actions, Forced Effects, Constant Effects, and Keywords... and, according to page 15, Actions can be played "in response" only to Actions.