My boy Hot Rod went thru lp surgery as his went from a grade 1 to a 3 or 4 in a matter of months. His tendon was on the side of his little leg and it was causing his leg to bow out. He did fine with his surgery and his knee is 100% now. I would definitely seek a board certified surgeon who is familiar with smaller animals. A lot of people agree that if it is not bothering the dog, then the surgery is not necessary, totally up to you and your vet/surgeon. In our case it was necessary because he did not want go for our walks which he loved/loves.
As for the separation anxiety, try leaving the room for very short periods of time (seconds to start off with, increasing it to minutes at a time). Your little one will get used to see you return and hopefully this will help. Also someone suggested putting a seat in front of a window so she can see out when you are not home.
Good luck and let us know how she is doing.