I have a feeling the horn and lights work when it dies. I am sure I would be just like you, just getting my rear end out of the road and not checking anything else. The problem is you can't just duplicate on demand. Since it would start to work after you turn it on and off, makes it sound like a bad switch contacts. The ignition switch is about $30 and easy to change (on my Series 1). . I would go ahead and replace it. Just make sure you disconnect the ground cable on your battery before you do it. Locksmith should be able to rekey it to match your doors. Like your comment on the clock. I use to take my out and clean and oil and it would work for about a month.
