I had a chicken that was hatched with a deformed leg which got worse as she got older. She never could use it and eventually it stuck out straight or over her head and got hung up in everything. I eventualy amputated above the hock. She did great with the surgery, healed well/quickly and go along much better by hopping on the one good leg she had always used. The sad part, about her story, is she eventually got a very bad, deep cut on bottom of foot under two toes and it developed into a bad infection that woudn't heal and kept spreading up her leg. When she could no longer get around, we put her down.
I also have a rooster right now that has been missing a foot for over a year. Gets along great.
So, yes they can get around with only one leg.
Also, there will always be a little "pecking order" taking place when you put a bird back with the flock. The less time they are away the better. I would just watch and make sure it doesn't get out of hand but normally it runs its course very quickly.
