Yes she should calm down after the litter, although removing them might stress her out. But I agree if she kills ones more they may have to be removed - however its perfectly normal for mom to kill babies that are weak and eat them. You have to deciede if what she is doing is natural or not.
If you deciede to hand feed them, good luck. Its quite easy to do, but may take a while until they get the hang of it. Dont let it dribble into their nose, wipe any excess on a piece of tissue. Id say feed every two hours and offer a heat pad on a VERY low setting during the night time. You also must get a warm wet piece of tissue or cloth and wipe their genitals after each meal, as this helps them go to the toilet and stay clean. Make sure every baby gets a full belly of milk each time, and goes the bathroom - it can be alot of hard work. I agree with using a human formula too
Good luck