keep the kittens and your girl seperated for now-they know each others their so just allow your girl a day or so to realise they're not a threat
The black marks near their noses could be part of their markings/color and as for eating a little, maybe try them on some rice pudding (tepid/cool) in temp and see if they show interest-if they don't dunk their paws in it and they will clean themselves, it may take a short while and you have to keep trying but you can get them eating and at this age-given that they leave you in a week-they need to be eating
Good luck with eating and keep us posted on how they and you get on
Your girl is hissing coz she's confused and unsure about whats happening-she will settle soon enough