Sometimes, but frustratingly often, the front passenger side door will not catch on close. We fiddle with the latch and door handle and the locks and the automated locking features, and it finally does, but it's a mystery what's wrong or what makes it work.

Any ideas/suggestions appreciated.

Close or lock? First it's check the wiring at the door/body junction. There's a rubber boot protecting the bundle of wires going from the car to the door. There might be a split in one of those. Also a loose connection behind the door card. Either way I'd take the door card off and have a snoop around, reseating the connections to the door module and lock actuator.

The lock works fine, it's the catch. The door simply will not close. It just bounces back open. Also, in a new development, the window on that door has stopped working. Could these be related? Is the door catch (not lock) electrical?

Is there a link to a diagram of this system?

Also, is there info on removing the door panel/card? Will I break clips and need replacements for it? Tools needed?

I'd try lubricating the door latch first. Spray WD40 or anything similar in there and exercise it a few times and see if it helps.