Advice for new dog

We have adopted a beautiful sweet momma dog. This asshole had her chained up outside constantly and i think abused her. She lost her first litter of puppies and had a second. When my moms friends took her ( she’s been chained up outside a disgusting house with huge rats running around😣) My moms friends went and took her off the chain with 2 of her most recent puppies (the only ones left) and the owner that kept her chained up watched them and said “Good deal” and they left with momma and pups. My grandmother adopted one of her puppies and now we have mom. She will still see the puppy all the time. My grandmother lives less than 30 min away. Another family adopted the other puppy

Anyways, the mom has attached herself to me. It’s the sweetest thing. She’s currently laying on the couch with me asleep. I’m worried about her. I just want advice with how to approach this. We have another dog and they met and did okay, and i have a cat who is mine and he does fine around our dog but haven’t tried with any other dogs around my cat lol. Anyways, again, lol she learned how to climb up and down stairs today!!! But she hasn’t ate/drank yet which i’m sure is normal considering i don’t know if they fed her regularly, she’s really skinny. How can i make her feel more comfortable? Also how i can i make sure she’s eating enough? It breaks my heart that she’s so scared and worried but i’m so glad we saved her.