When my mediport was placed, I was supposed to start chemo the next day. Usually, the discomfort is minimal, but I had a rare complication, where I had to have my port replaced the next day. Generally, tylenol is all that is needed, tho you feel like you've been hit in the chest with a bat.
Ask about Emla cream to gob on over your port prior to your chemo treatments. That way, you don't feel the needle going in. For some reason, most drs don't think to order it for you; everyone I know heard about it from another cancer patient. You may not be able to use it the first time, as your incision from the placement will need to heal, but a week or so after the port is placed, you can use Emla.
Drs differ in how long they want you to keep your port after completing chemo. I had mine out relatively soon; I know others who kept theirs for a year or more post-chemo. Removal is about the same as placement - you are sore, but it is not a big deal. I had my placement and removal done with just local anesthetic, and was fine with that.