True... except the people who believe in such things have been told that killing is a sin. Whether it's something that is endangering salvation is the more unclear question.
Yes, although even among people who believe, there are sharp differences of opinion on the subject of killing and what kind of eternal punishment it might entail. But many also believe that God forgives people of their sins, if they confess and ask for forgiveness.
This is where the whole idea always got a bit murky for me, considering all the things that are considered "sins" (besides murder). A mass murderer could ask for forgiveness at the last minute and go to Heaven, while an unrepentant coveter of thy neighbor's wife would be burning in Hell.
One of the biggest problems atheists and those of lapsed faith have with religion is not understanding what God's plan for us is. It's a fair point- how do you know how straight a path you must walk, if no one explains to you how not to stray and what the goal is?
I don't really think there is any "plan." For all anyone knows, "God" could be some advanced alien scientist who tried to do an experiment which failed. We could be nothing more than a bizarre side effect. I don't think religion knows any more about the "Great Unknown" than anyone else does, but what they also teach is that "we" as humans are special. It's often said that "God loves us" and "God has a plan for each and every one of us." Religion has more to do with "us" than it has much to do with "God," which is an indefinable concept anyway.
But the whole emphasis on "sin" and forgiveness makes it seem like God really cares that much and that "we" are the center of His universe. Does anyone really care if an insect kills another insect? So why would God care if one animal kills another animal? Why would He care about anything we do? He has to run the entire universe, so why would people think He'd be concerned about little old us?