Please clarify which light schedule you are following: human, solar or the old 12L/12D because it makes a difference.
If you are Elvis' human, your husband should not be interacting physically with him yet. Contrary to what people believe and expect of them, parrots are not family pets. They are one-person pets that learn, in time, to tolerate and even like the rest of the family. But this takes time and it implies the other people not presuming on a relationship that is not there yet (parrots are not patient with presumption, especially when it involves touching their bodies). I suggest your husband ignores you and Elvis when you are all in the same room and interact with him only when you are not around and without any sort of physical touch. He can let Elvis out of his cage, talk/sing/whistle/dance/play with him and even move him from point A to point B but only on a T stick. The worst thing you can do is to establish a biting precedent with a parrot and your husband has already done this so he needs to be super vigilant and never give Elvis another chance (reason) to bite him because he now needs to undo the damage so he can start again on square one of the good path with him.
I don't know what you mean by 'clicking'. Amazons make a clicking noise in their throat (it sounds like a rapid Cahcahcahcah) when they are overly excited and angry (could Elvis have leaned it from Blue?) but cockatoos also do a clicking noise only it's by opening and closing their beak rapidly so the upper part, hitting the lower part make a noise very similar to the one we can make with our teeth. My Freddy does this with me every single morning. It's his personal 'thing' with me - but only with me and nobody else. I am not 100% sure what this does for him or what it means but he is extremely insistent and consistent about it - and he follows an actual protocol that he never deviates from: he asks me for it (he goes 'Pahpahpahpah' to me) and, when I agree, he climbs on a perch placed at my face level and putting his face about one inch from mine, he turns it sideways (always to the left) and starts doing it (I have to do it, too, and I have to follow the same rhythm he does) while staring straight into my eyes and stretching out his right foot for me to hold it in my hand and caress it with my fingers. This makes me believe that it must be a wooing (breeding) behavior or display that males do to females. Now, if Elvis is over 2 years of age, he is already producing sexual hormones and, if he has been fed and is still been fed soy and not kept at a strict solar schedule with full exposure to dawn and dusk, he could be already sexually mature -the burrowing into the blanket (cavity) is also a breeding display. People say that cockatoos become sexually mature between 3 and 5 years of age but, in reality, this is the age they become sexually active - they start producing sexual hormones way before they become active.