I've not got the book with me, so this is from memory, but I hope it helps anyhow.
Crippling Shot: It most likely doesn't specifically state in line of sight, however, I would likely play it as it has to be. So, RAW, you can shoot through trees/your own unit. RAI (rather, what I'd imagine was intended), LOS is necessary.
Epic Strike: Terror is caused in the charge phase (I can't remember if it is tested then or in the fight phase), but Terror comes first, so I'd imagine that, unless it states otherwise, that you can negate it, using RAW. If you decide that they can't or it states that, just imagine that they're a little too scared to be all epical