I've got to say, I don't get why 'som' is in use here. Can I use 'hvem' instead or is it wrong?
"som" is a relative pronoun used to begin a relative sentence. It points back to "Gruppen". It works just like "who", "that", "which" in English. "hvem" would not be correct here.
ok tusen takk Alek
Mennesker uten syn would mean people without sight?
Yes, it could mean that.
Could folk be used here instead of mennesker?