What is chance that nissen fundo by highly skilled surgeon will last forever? what is lifetime chance of redo? what % still have reflux post-surgery?

Unlikely: A skilled surgeon frequently report recurrence rate < 10% in 5 yrs. The number can easily double in 10 yrs. Keep in mind the true recurrence rate isn't usually known for any surgeon. I do redos on patients who refuse to return to their 1st surgeon - I am sure a few of my patients go to other docs too.

None: There is no lifetime guarentee for this repair. Many are asymptomatic even with x-ray proven reflux after surgery. If done correctly reflux will be gone immediately after surgery.