99 GTP: Key cylinder replacement

Several times recently, I have had a no crank condition when trying to start the car. Turn the key to start, dash lights go out, but no crank, no audible solenoid click, nothing. Turning the key to off and retrying (two or three times) resolves the issue...car fires up strongly. I figure must be a connection problem (switch or relay).

I suspect a bad key cylinder. The key cylinder "sticks" sometimes when turning off the car. Sometimes the key will be removed when not turned all the way to off. So it is showing symptoms of wear.

I don't know if there is anything special about the keys that could contribute to the problem. (I don't think it is a PK3.)

How can a bad key cylinder cause the no crank issue?

I didn't find a relay in the schematic for the starter circuit which surprises me. (I have a 98 FSM, not 99.) I had thought there was a relay under hood that may have gone bad. Can anyone confirm the presence or absence of a starter relay?

How can a replacement key cylinder be configured for the current key? I would prefer not having separate key for ignition, different than doors.

Any guidance is appreciated.