I think for 4. its mostly because he is the only one who can really sense if someone is infected or not and therefore eliminate them before they show symptoms whereas someone like hana would have to wait until they have “turned”. Right?? Plus he can just use his powers in a setting where there are infected and healthy people all at once and only the infected would die. Hana would just kill everyone with no filter or shed have to collect all the imfected people first and seperate them from others
As for the others im really not sure but my thoughts rn would be 1. I think their bond is extraordinarily strong, especially with saks core changing for lima and everything but i also think it wasn’t really explained that much why that is
2. i guess maybe he can still understand limas thoughts better than others but the amplifier just made their connection even stronger?? Idk tho
And 3. As far as i understood all callers are like that but what i didnt understand was whether core users can also have more than one caller?? Because hana was telling lima something like “you arent even that special to him” right?

Not sure if it's because of the fan tranlations or maybe I read too fast, but can someone confirm with me my thoughts?
1. The amplification device makes the core possessor more attached to the caller? If without it, the core possessor can become unattached?? If so, then does that mean Sak and Lima aren't "officially" caller and core possessor???????? (By officially I meant they were meant to be bounded w/o amplification like Hana and Nana)
2. Continuing, Sak seems to be unable to sense Lima's thoughts after the amplification device was destroyed. Was the hearing and feeling the thoughts of your caller an actual symptom of caller and core possessor bounding or just a byproduct of the amplication device?
3. Callers arent bounded to one core possessor? They can have many? Hana explained Lima has a natural ability to pull core possessors into protecting him, explaining why Echo chose to die in order to save Lima. Is he like an 'ultimate' caller??? Or are all callers like that in general?
4. Looks like Sak's ability burns infected (or people I guess) on a large scale as well, just like Hana who does large scale damage. So I wonder what makes him "different"? If the goal is JUST to kill the infected, rather than "cure" them, then anyone with a core that can impact large scale will do and it doesn't have to be Sak, right??? (And I understand they said the whole spiel about how his core only affects infected, but I'm saying if the goal is to just kill infected, then that renders his core the same as everyone else and someone like Hana could've done it as easily too)