Not advisable. Your doctor will tell you that you may develop a infection called peritonitis if bacteria in water enter your cathetor, not worth the risk.
Yes, but carefully. National kidney foundation recommends swimming as good exercise for patients on peritoneal dialysis. However you should check with with your dialysis unit, as each has it's own policies regarding bathing. Some drs will advise against because of percieved risk of peritonitis. Catheter entry site plus entire catheter tip can be covered by tegaderm which seals the area from water and bacteria.
Swim with PD. This is an age-old question. Answer is yes. Best place to swim is a chlorine pool that is well maintained. River is not good. Lake is not good.