I was reading a biography of U.S. Grant, and it stated that after the capture of Vicksburg he paroled 30,000 captured confederate troops. The book went on to say that those captured had to promise not to take up arms again until officially exchanged.

This raised a few questions for me.

1. How did paroled troops find out if they were officially exchanged and allowed to take up arms again?
2. What would happen if a soldier broke his word and took up arms without being exchanged? Would he be imprisoned or have other significant negative consequences if he was captured?
3. How often did troops return to the fight after being paroled?
4. Were they treated decently when they returned home? Were they pressured to go fight again or did people generally leave them alone until official exchanges?
5. How often did exchanges actually occur?