Fargus

Hey guys, so I have never played Aos or any war game for that matter but finally resolved to start a LoA list. I plan on buying a black shard warhost and daemonsmiths to start and then adding an artillery battalion down the line. As a new player I have two major questions, my original plan was to have three death shriek rockets in the battalion so I could spread them out to cover against deep strikes and coming on from off the table edge, but would it just be better to use three magma cannons for the mortal wounds? And I haven't seen any mention of it so the next question is with the iron daemon would it be good to run an emerald life swarm with it so I can just power up to 4d6 every turn and just take the d3 or are there just better options to pursue?