Curate, connect, and discover
I will steal your socks and souls.
So, with what we could read and learn in CQ3, it showed that they were like, some sort of cats who need souls to nourish themselves, and so I think they're some kind of Lyche, who are conscious zombies with magic(I don't know if it's their names in English) or they are cats spirits who consume the souls of others to live longer by resentment.
With that conclusion, it means they are cats who don't go to the Purrgatory and rest haunting places, or that they are rituals in the game for becoming immortal, since it's what Lyche do (the only problem with that is that they need to sacrifice a soul for becoming one and that after it's theirs principal source of energy. )
I don't really think we can really go further about that for the moment so let's go with my head cannons !
Meowtallika's crew are, for the majority, his fans -most likely other pirates- who ended up becoming Lyche by the influence of Meowtallika
Meowtallika can't hear the silence (the iiiiiii sound, or an alarm) , since he is in a loud environment most of the time, which disrupted his hearing capability.
The crew who are playing the other instruments with him are his right-hand men, and they regularly have a meeting about the last concert, which ends inevitably in total chaos.
Meowtallika can't sleep, since he's no longer 'properly alive'
It's rare but when Meowtallika has an art block he shuts himself in his room and destroys everything he can, before sitting down in the mess he created for hours.
Meowtallika's crew avoid the sun as much as they can, it burns them slightly.
They glow in the dark at command so one time when a rat from the pi-rat crew asked for a lamp the representation of Meowtallika's crew just started to glow.
And that's all for the moment, good night.