We brought Mason home just last week so I know how you feel... He is my first puppy and an absolute gem, I have been running around like he is made of glass! Loose stools is something he suffered from too, and is apparently normal during the settling in period, though the food the breeder started him on isn't the greatest. He wasn't too keen, so we have slowly changed his diet to another brand. I'm not sure if he is feeling more settled, or whether the change worked, but he is now pooping normally. Never though I would be so relieved to see a solid poo
As for eating, he can be a bit funny. He was fickle when we got him home, but we fed him from our hands and he soon started eating. How many times a day are you feeding her? Mason gets 4 or 5 meals a day at the moment (he is slightly younger than Laila, he is 7 1/2 weeks).
He also sleeps a lot. In fact my cuddles seem to knock him out cold every time! He must have a very boring Dad! But seriously, he runs around like the devil is chasing him for 20-30 minutes, then will crash out. In the evenings he sleeps for hours! We had our first non-whining night last night, very proud of him.
Hope this helps. Try not to panic, Laila has just been taken away from Mum, and has been left alone by her new Mum and Dad. She will get used to it (Mason is already starting to understand that being left is ok, we do come back and he gets a tasty treat when we aren't there).