Hey, Julie.
Welcome to our pack.
Don't worry too much. When you introduce a new dog into the home ALL the dogs go through a period of adjustment.
Growling at the other dogs when she is near you. . .She is simply protecting YOU. You are HER pack leader and she doesn't KNOW or TRUST your other dogs yet.
Food aggression is common even amongst pack mates who have grown up together from puppies. Simply feed her apart from the others until she has integrated with the rest of your pack.
As Sarah says YOU control the food.
Do not worry it takes several days or weeks for some dogs to "feel at home".
OK the next bit is not intended to scare you, just making you aware of something that may happen, and if it does it is quite normal.
Do not assume though that she will simply slot into place at the bottom of the pecking order
And whilst they are sorting out the new hierarchy of the pack it can get quite tense.
Sometimes this does escalate into aggression. This can and does look like they really are fighting, however. . .
It rarely goes beyond a lot of noise and open mouths and tussling as they try to force the other into a submissive position.
Either gripping the throat or the back of the neck.
We used to foster dogs for a few weeks until they could be properly re-homed. Once we introduced a Chihuahua when we already had a Pomeranian, and they were a whirlwind of tooth an nail and fur for 24 hours. . the next morning they had sorted out who was boss and were best of friends.
I hope everything works out for you, well done for taking this lovely dog into your home.
Best of luck.