Tom,
Sounds like you have done most of the actions to get the engine to fire. All the S1's seem to experience the clicking at some stage. A couple of things have helped for me, a new battery every couple of years and disconnecting the battery every time I put the car in the garage. I used a conditioner for a number of years and this seemed to kill my battery quicker so I have not used this for 2 years. You might try to call Keith at BHM who has a lot of experience with the S1. His suggestion to me some time ago, was to put the ignition on then press and release the starter button rapidly for 10 seconds or so. He also feels that not using the car often enough causes a light corrosion to build in the starting circuit.
On your other question the starter motor can cook in the engine bay which seems to cause premature failure, I had mine changed with Millers Commercials in High Wicolme 3 years ago. They have perfected a technique which accesses the starter from the side, this saves an engine lift. Others might be doing this as well.
Dave
