Are the custodians of Paradise and Hellfire existing now, and are the angels of torment and mercy mentioned in the hadith of the killer of 99 souls the custodians of Paradise and Hellfire?

Paradise and Hellfire exist now, and each has its guardians. It is mentioned in the Hadith that whoever asks Allah for Paradise three times, Paradise says: "O Allah, admit him to Paradise." And whoever seeks refuge from Hellfire three times, Hellfire says: "O Allah, protect him from Hellfire." This statement could be taken literally or metaphorically.

As for the angels of mercy and the angels of punishment, they are the ones who take the souls after the Angel of Death. The angels of mercy take the souls of the believers, and the angels of punishment take the souls of the disbelievers. This is indicated by what An-Nasa'i and others narrated, that when a disbeliever is dying, the angels of punishment come to him, and when a believer is dying, the angels of mercy come to him. So, the Angel of Death takes the soul and then hands it over to the angels specialized for it.