"Just about functioning" is pretty impressive, and utterly exhausting. However you're doing or feeling, yes, it's normal. These times are not a linear progression through feelings, happily or sadly, it's a good old tangle for quite a long time. I say "happily" because surprise moments sneak up on you, of amazing memories or jokes you shared. And those moments are things to cling to, especially while you're trying to get your head round the "nevers" and the emptiness.
I am no professional, but my guess is your children are partly trying to protect you from their pain, because they can see yours. This will work itself into balance, and become something you all share, but for now you may just all be clinging on. I found it helpful to keep mentioning my husband's name, bringing him into conversations where I usually would - it seemed to give other people the hint that it was very much OK to talk about him. Later, this gives low pressure opportunities for your children to talk about missing their dad, without them having to find a big moment.
Inquests and investigations are even tougher, maybe because they imply there will be a reason for everything, an injustice corrected. And that's only partially true - every loss of a hugely loved person is unfair, is impossible to find a reason for, and eventually the inquest answers cannot answer the unfairness of it all. Anger is so powerful and consuming it's scary, and frightening for you to see in your children - anything you can do to help him ride it out, rather than hide it, will be a good thing. My mother-in-law drove up to the Downs and screamed her head off quite regularly (some startled hikers on those days!) just to let it out.
You're not mad about the phone things. I got my husband's voicemail message sent to me as a recording by his mobile company, before I could bring myself to cancel the contract. It used to drive me nuts getting his voicemail when he was alive, but later hearing his voice by any method was a comfort.
Hugs to you x