A 3 yo people needy dog wont go potty outside

Question
A year ago I adopted a slender 1/2 Aussie Shepard, 1/2 lab.  She spent a couple weeks at the shelter, and her surrender papers stated she spent her first 2 years outside only.  She is lovable girl.  Constantly wants to be with-near-licking us.  Licks toddlers face instead of biting; they get along great!  She only barks, and gets protective, of strange looking people ~ Good judge of character.  Walks on leash, crate trained, loves dog park (although she stays close to me), takes orders fairly well.  The problem is she is so attached to being near us, she won't go in the fenced back yard unless we go with her.  Fights to be pushed out the door to go potty and jumps on walls under windows to get in.  She'll hold it in and not go potty.  Then she'll pee in the house about 1-2x a week and hide in her crate.  She will go out the front door to hit the spots she's seen all the dogs walking by go to.  Problem is, she'll then run the neighborhood and it's prohibited off leash.  How to I break her fears to go into the back yard w/out us?  And do we need to work on breaking her need to be constantly next to us?

Answer
Any dog with Aussie in them can be "clingy".  This is a breed that likes to be near its people.  Most dogs do not like isolation, but in these dogs it can be a bit extreme, since they were bred to work so closely with humans.  It isn't necessary to try to break her of the need to be with you when you are at home (If you don't like that kind of dog, next time get a more independent breed LOL - my hound lies on the couch and doesn't bother us, the Aussies are always nearby.)  
As to the housetraining, she may never have realized that she should ONLY go outside, since she was kept out.  Don't just shove her out the door - go with her!  That gives you an opportunity to reward her for going outside.  Also, never punish an Aussie or Aussie mix for indoor mistakes - they are fast learners, and may learn that it's dangerous to pee in front of the human, not just that they shouldn't pee indoors.
Once you have taken her out, and she's back indoors, supervise her any time that she is out of her crate (I tether my pups to my belt.)  Then, you can interrupt any "accidents" by gently saying "eh-eh" and "Outside?" and guide her out again.  If she goes, reward.  If she doesn't, back in the crate or on the tether.  Aussies are quick learners, especially if they are getting rewarded (and not punished) for going outdoors.  Both my Aussie and my Aussie mix only had 2-3 accidents before they realized not to pee or poop in the house, and because I say the word that describes the function each time, they now also "pee" or "poop" on command.  It's funny to see, but sometimes my younger dog will squat anyway when I say "go pee", even if she doesn't have to urinate!  Nothing comes out, but she is so proud of herself just the same LOL.  Good luck and let me know how it works out.