I have 3 boys,
Routine is a big part, these know what to do when they hear the food going into the bowls, i have placemats where they are fed, i come into the room and they are sat waiting , they then stroll round outside then lay down, 2 hours after eating they are walked, i do training every day on walks, stay , here, freeze, leave it.
They have leash work and off leash.
Each dog when younger had walks individual as well as together every day,
Now its all together,
Your girl sounds like shes in a fear stage, the noises she doesnt like ie the car engines, how do you react when she does this, budcuss used to hate motorbikes , so a friend sat a distance away and kept reving his bike gently , id get bud to sit with me id ignore him and every time he relaxed id get closer, he soon didnt bother, but if your dreading how she is going to react she will pick up on that , be positive, get her to sit dont let her back away, dont fuss her anxious behaviour, when the noise as gone move forward.
Her toys, if shes gaurding them id take them up and give them to her when you are going to play or if its in your routine to give her a toy when your leaving her alone ect, shes got to earn her freedom .
Does your friend walk in without knocking, because i would strongly advise against that, tell them to knock or shout hello .
The work you put in now will give you many years of the most loving loyal protective bundles of drool .
If you want to ask any questions i read the forum every day
Good luck