Donating a kidney. Risks include surgical complications, having only one kidney for life, and developing progressive kidney disease due to underlying illness that might develop. These risks are all low. Another important risk is regret that you donated for the wrong reasons, such as guilt or feeling pressured. It is important to feel committed to a live donation for good reasons and with no outside pressure.
See below. The proceedure of retreving the kidney is the main risk. It can be done laparoscopically or may need open surgery. Very small surgical risk having one kidney is enough to carry out the body functions, obviously if the kidney is injured or blocked by a stone that is the only one.
Surgical. There are rises from the surgery. Hernia, bowel obstruction, infection, anesthesia problems, blood clots, bleeding, and very rarely death. There is also potential risks (in the future) of kidney disease in your remaining kidney.
Depends. I assume you are asking about living kidney donation. The donor surgery is done under general anesthesia and the mortality rate associated with the surgery is 0.02-0.03%. So even though it is a very low probability, there have been deaths associated with living donor surgery on very rare occasions. As with any other surgery, bleeding, infection, and blood clots in legs (DVT) can occur.