Can anyone explain the best way to get to the starter motor, so I can inspect it and it's wiring? From the bottom, or from the top?

 

From the top. You need to remove the top heat shield (two bolts), the header (eight small bolts on the engine plus two after the cat, plus the electrical connectors for the two O2 sensors) and finally the lower heat shield that covers the starter among other things (one bolt and it slides towards the passenger side). You will then be staring at the starter. Note also that the lower heat shield also has some wiring beneath it, and in some cars, the wiring gets chafed by the shield. This is a good time to inspect and repair any damage to the wiring. The stater is held on by two of the transmission bolts, which are pretty tight.

The header does not have to be removed from the car. Just remove all the bolts and lower it down and back to gain clearance. Also, it's a good idea to have the exhaust flange gasket for the pipe and the head-end gasket as well before starting the work. These two parts are cheap, I got them for less than 10 dollars from Classic Mini.