I have read a lot about sling for prolapse repair. What is involved in traditional suture repair? What is overall success rate? Possible complications?

Failure. Traditional surgical repairs that use just sutures have been reported to have failure rates as high as 40 to 50% by some. These procedures are often referred to as a&p repairs & sacrospinous ligament fixation. Complication such as infection, bleeding, pain, injury to urinary bladder & rectum, and failure of the repair are the most common.
Sling 4 incontinence. A sling is an outpatient procedure that is now gold standard for stress incontinence. Choices for prolapse repair include: vaginal vs abd vs l'scopic or robotic; native tissue (trad suture) vs mesh augmented; and w/hysterectomy or w/o. The right choice depends on age, activity level, first surgery or recurrent prolapse, health, & risk factors for recurrence or complications. Consult a urogyne.