Just the ignition switch will take care of everything. You don't need to bother with the key cylinder. If you replace that, you'll have to get it re-keyed at the dealer. The ignition switch is at the end of the locking cylinder so when it breaks it causes the locking cylinder to act weird. The locking cylinder is metal so it's difficult to mess up. The ignition switch is cheap plastic.
I had the exact same type of problem. A/C quit working, radio freaked out. Then the key was hard to turn. Then it would not go in without a lot of coaxing. Then it wouldn't turn again. Etc, etc, etc. Replaced the little, plastic ignition switch and everything's copasetic.
Unfortunately, it's a very common problem. Enough so that I ordered 3 switches just in case they stop making them. RandallNeighbor just had to do it too and two people on another forum I like to visit. I even ran into one when I was test driving them before we got ours that was doing the "no turn" thing. I didn't know about the problem so I don't know if the dealer figured it out or not.
