First, let me say thank you for rescuing this girl.
My thoughts on the poo issue are that her system will settle down after consistent feeding with a good food. I think her body just needs to adjust.
As for the shyness and being scared of new people/things... this will take time. Don't push her to do too much too fast. People on here talk about a 2 weeks time out, where you don't introduce new people or experiences to gave her a chance to relax.
I am sure people with more experience to give you good advice here... so I say... read, learn and love.
: 5 year old (DOB: 8/31/2008) GSD rescued 10/15/2011
Everyday, we get closer